The present invention relates to an improved-cut machine for cutting blocks of stone. In particular, the present invention relates to a machine for cutting stone blocks such as marble, or granite or natural stone in general, using diamond or non-diamond blades. In fact, not diamond blades but metal blades (iron) are used if the machine has to cut granite, with the interposition of an abrasive mixture (so-called slurry) essentially consisting of metal grit, lime and water. Machines of this type are known, consisting of a load- bearing structure beneath which at least one block to be cut is positioned, such a load-bearing structure comprises a blade frame inside which at least one cutting blade is positioned longitudinally. The machine comprises means for generating an alternate movement in such a longitudinal cutting direction and such a frame is provided with means for moving the blade frame in a vertical direction towards the block to be cut or vice- versa, meaning that the block moves in the vertical direction towards the blade frame, which is fixed.

The blades consist of a metal structure on which diamond plates are positioned which define the hardest portion that cuts the stone blocks. On machines with metal blades, the abrasive mixture determines the cut. A machine of this type is described in patent EP1089859.

The aim of the invention is to facilitate the operation of consuming the material being processed by the diamond blades, by imparting to the same, through the blade frame, an additional vibration motion to increase and facilitate the cutting effect on the material itself .

One aspect of the present invention relates to a machine for cutting stone blocks by means of diamond or non-diamond blades, having the features of claim 1.

The features of the present invention will become more apparent from the following description and from the accompanying drawings, relating to an exemplary non- limiting embodiment, in which:

• figure 1 shows a side view of an embodiment of the machine for cutting stone blocks according to the present invention;

• figure 2 shows a top view of the same machine in figure 1 ;

• figure 3 shows a perspective view of a blade frame of the machine in figure 1 ;

• figures 4a, 4b and 4c show front, side and top views of the blade frame in figure 3.

With reference to the above figures, a horizontal machine for cutting blocks comprises a load-bearing structure 2 having four columns 21 connected at the top by longitudinal members 22 and cross members 23. Inside the bearing structure is a frame or blade frame 3 and a base 4 on which the block B to be cut is placed. The blade frame slides on vertical guides placed on such columns 21 so as to be lowered towards such a block. In one embodiment, the load-bearing structure is supported on or attached to the floor, while the connecting rod/crank system only moves the blade frame, which comprises a fixed part associated to the mentioned vertical guides and a movable part which slides horizontally with respect to the fixed part and it is connected to the connecting rod. The cutting blades are constrained on such a movable part.

In another embodiment of the machine, such a load- bearing structure as a whole is horizontally moved in an alternate motion by a connecting rod/crank system 6. In fact, in this embodiment the structure is engaged in horizontal guides placed at the base of the structure itself that allow it to move horizontally.

Such a connecting rod/crank system comprises at least one connecting rod 61 and at least one crank 62 coupled to a flywheel 63 which regularises its motion. The shaft of the flywheel is set in rotation via a belt 64 which connects it to a motor 65.

Such a frame supports the cutting blades, which are arranged longitudinally side by side.

The forward-back movement imparted by the connecting rod/crank system and the simultaneous lowering of the blade frame causes the cutting of the block.

The lowering of the blade frame is imparted by a motor- reducer system positioned on the frame, which imparts the vertical advancement motion to the blade frame.

In a further embodiment, the blocks are positioned on a block carriage rather than on a fixed base, which is raised progressively during the cutting (feeding motion) , while the cutting motion comes from the blade frame .

In order to cool the blades provided with diamond plates or sectors, water is sprinkled on the blocks to be cut by means of a suitable system. In frames with abrasive mixture with grit, the sprinkle consists of such a mixture .

The blade frame 3 is a substantially rectangular or quadrangular structure comprising plates 31 having a high flexural rigidity mutually connected by means of two struts 32 called stringers. Appendages 33 are formed on one of the two plates for connection to the connecting rods 61.

The pack of blades 34 (shown in figure 4c), supported by this structure, is put under tension by a mechanical or hydraulic tensioner which allows tensioning every single blade and maintaining a constant tension during the cutting process.

Two travel end sensors define the limits of the vertical ascent and descent movement of the blade frame. Two encoders, positioned on the frame at two of the four set screws, control the movement of the frame and check that it is parallel. A mechanical system controlled by a sensor checks on both sides of the block that there is no breakage of a block, in which case the device stops the machine in an emergency.

According to the present invention, the blade frame is equipped with at least one device for generating vibrations to be imparted on the blade frame itself. Such vibrations are preferably imparted in a vertical direction of adjustable amplitude and frequency, so as to adapt to the various types of possible materials of the block being processed.

Preferably, a device is positioned for every angle of the frame and in this configuration, the devices are synchronised in terms of amplitude and frequency at least in (front-back) pairs.

A device for generating vibrations according to the present invention, among the other possible configurations, may consists of an eccentric rotating mass set in rotation by an electric motor; the rotation speed determines the frequency, while the value and the eccentricity of the mass determine the amplitude of the vibration. A possible alternative solution provides for the magnetic formation of vibrations, in particular by means of a coil and a suspended mass.

A suitable amplitude of the vibrations should be of the order of ½ ÷ ¾ of the diamond grain size (equal to about 2 tenths of a mm) of the blades, i.e. 5-10% of the size of the metal grit.

The positioning of such devices for generating vibrations can be advantageously associated with means which allow the horizontal movement of the frame in guides of the load-bearing structure.

In particular, such means comprise sliding blocks 35 that slide in the guides of the support structure and that allow the horizontal movement of the frame.

In particular, with reference to figures 3 and 4, the sliding blocks 35 are connected to the frame by means of arms 36 on which such devices for generating vibrations are inserted. The arms are connected to the sliding blocks with the interposition of first damping elements 37, preferably elastomeric. Similar damping elements are positioned also in the case of movement obtained with oscillating arms. Moreover, also the connection of arms 36 with the blade frame takes place with the interposition of second damping elements 38.

Finally, the connection between the appendages of the connecting rod foot and the blade frame takes place with the interposition of third damping elements 39. Such damping elements as a whole are suitable for preventing the generated vibrations from propagating in the direction of the guides.