Description

The present invention relates to a grooved, diamond blade with sections (or sectors) made by free-sintering applied directly using laser welding.

More particularly, the present invention relates to a carbon steel grooved blade, wherein the sections (or sectors) are formed of bodies having a substantially parallelepiped shape, with the surface made abrasive by the presence of synthetic diamond granules; said sections (or sectors) are directly bonded to the lower surface of the grooved blade by laser welding. A grooved blade of this type is especially suitable to be applied to machines that cut and square marble, granite and stone materials in general.

It is known that to saw blocks or slabs from blocks of marble or granite and for cutting stone materials in general, blades of the so- called“Fc grit" type, or smooth blades provided with diamond sections (or sectors) are traditionally used; these sections (or sectors) are anchored by hot brazing to the blades, which are moved by special single- or multi-blade machines.

The diamond blades on the market today define a structure of significant dimensions "referring to blade height”, on the surface of which sections (or sectors) are brazed made with “Hot-press” technology and with a Cobalt content close to 100%; these sections (or sectors) have a conical cross-section to operate the blade in a straight line with the cut. The surface of the sections (or sectors) connected to the blade is made abrasive by the presence of granules of synthetic diamonds. A traditional diamond blade thus comprises a steel plate-shaped body, which is generally reused by brazing the sections (or sectors) on it several times. However, this well-known and widespread solution has major drawbacks.

The blades of this type, in fact, show limits in terms of the absorption of vibrations caused by cutting stone and the stresses resulting from cutting actions, with the consequence of a limited operating capacity over time, sometimes accentuated by the fact that the abrasive sections (or sectors) can detach from the blade itself.

Moreover, these blades are not constantly able to ensure the adequate support of the various sections (or sectors).

In addition, in order to optimise costs, these traditional blade- bodies are reused several times for the assembly of the sections (or sectors); this results in mechanical alterations TAZ (Thermally Altered Zones), which can compromise the life of the blade itself due to the formation of cracks caused by brazing.

For example, GB 1 206 736 refers to a diamond, grooved blade for cutting marble, granite and stone in general, comprising a plate shaped body constituting the blade. The lower edge of the latter bears multiple sections (or sectors) or teeth spaced apart, engaged with the blade-body, the surface of which is rendered abrasive by granules of synthetic diamonds; the cutting forces of the blade are appropriately distributed and the sections (or sectors) are suitably cooled according to the different operating conditions.

The solution of making an abrasive tool such as a blade is also known from EP 0 925 378, wherein the sections (or sectors) or teeth are made by free-sintering technology with metallic powders comprising Iron and non-ferrous materials such as Nickel or Cobalt and are directly bonded, i.e. without interposition of a neutral connection sector, to the blade-body by laser welding.

The purpose of the present invention is to overcome the drawbacks complained of above.

More particularly, the object of the present invention is to provide a grooved, diamond blade having mechanical properties that allow an elastic modulus to be obtained suitable for the correct support and straightness of the multiple sections (or sectors).

A further object of the invention is to provide a grooved, diamond blade suitable to support the stresses from the cutting actions and to guarantee a reserve of tenacity for the absorption of vibrations from the cutting of the material.

A further purpose of the invention is to make available to users a grooved, diamond blade suitable to ensure a high level of resistance and reliability over time, in addition such as to be economically made.

These and other purposes are achieved by the grooved, diamond blade of the present invention according to the main claim.

The construction and functional characteristics of the grooved, diamond blade of the present invention will be more clearly comprehensible from the detailed description below in which reference is made to the appended drawings which show a preferred and non-limiting embodiment and wherein:

figure 1 schematically shows, in an axonometric view, the grooved, diamond blade of the present invention, by way of example without the abrasive sections (or sectors);

figure 2 shows schematically, in an axonometric view, the same grooved blade with the abrasive sections (or sectors);

figure 3 schematically shows an axonometric view of a blade similar to that of figure 2, but reproduced at a different angle;

figure 4 schematically shows an enlarged axonometric view of one of the abrasive sections (or sectors) on the blades shown in figures 2 and 3;

figure 5 schematically shows, in an axonometric view, a part of the blade of the invention, combined with a conventional fitting attachment of said blade to the frame of the machinery performing the cutting and squaring of marble, granite and stone materials in general;

figure 6 schematically shows, in an axonometric and comparative view, the same part of the blade of the invention combined with the fitting attachment of said machinery according to the prior art; figure 7 schematically shows, in a lateral view, the blade of the invention under pre-tensioning conditions;

figure 8 schematically shows, in a lateral view, the blade of the invention in the condition subsequent to its tensioning, to highlight the arch that it forms.

With reference to the aforesaid figures, the diamond and grooved blade of the present invention, globally denoted by reference numeral 10 in figures 2 and 3, comprises a plate-shaped body 12 constituting the blade-body, provided with opposite and known side attachments 26 for fitting to the frame of the machine (not illustrated); the body 12 defines a rectangular plan, with a maximum thickness of approximately between 2.5 and 6.0 mm and a height typically between 60 and 130 mm. The length of a blade of this type can reach and exceed five metres. The body 12 is made of steel with a high carbon content, C40— C70, and along its lower edge 22 the sections (or sectors) or teeth 14 intended for cutting are bonded, the surface of which is rendered abrasive by the presence of granules of synthetic diamonds; one of said sections (or sectors) or teeth 14 with cutting part 18 defines, for example, a substantially parallelepiped shape and is illustrated in detail in Figure 4. The sections (or sectors) or teeth 14 with the cutting part 18 bonded to the blade-body 12 are spaced apart depending on the type and properties of the stone material to be cut.

According to the invention, said sections (or sectors) 14 are made by free- sintering technology from a compacted set of different metal powders, including Iron and non-ferrous materials such as for example Nickel, Cobalt, Tungsten, Aluminium, Zinc, Copper, Chromium, Tin, Molybdenum, Vanadium, Niobium, Phosphorus, Boron, Silicon, Carbon, Magnesium and Manganese. At least in the lower part or interface part 16 of the sections (or sectors) or teeth 14, corresponding to the area in which they abut with and are connected to the blade-body 12, the concentration of Iron is higher than the upper part with the cutting part 18 of said sections (or sectors); said lower part or interface part 16 of the sections (or sectors) 14 in which the concentration of Iron is maximum, preferably with an addition of a very low percentage of Carbon, typically less than 0.1%, extends for the entire width and depth of said sections (or sectors) and for a height preferably between 0.1 and 2.5 mm. In the upper area with the cutting part 18, corresponding to the larger area of the sections (or sectors) 14, the powder base material mix is typically formed of Iron, Nickel, Cobalt, Tungsten, Copper, Tin, Molybdenum, Manganese, Phosphorus, Carbon combined in various percentages and synthetic diamond granules. The amount of Iron in the upper area with the cutting part 18 is limited with respect to the interface part 16 of the sections (or sectors) or teeth 14, where such metallic material is present in percentages ranging from 40% to 90% of the total mass.

In one embodiment, the powder base material mixture of the interface portion 16 of the sections (or sectors) 14 comprises a percentage of metals selected from the following: Nickel, Cobalt, Tungsten, Aluminium, Zinc, Copper, Chromium, Tin, Molybdenum, Vanadium, Niobium, Phosphorus, Boron, Silicon, Carbon, Magnesium and Manganese; the percentage of said metals, used individually or in combination, is between 1 and 40% of the total mass. The sections (or sectors) 14 are bonded to the body 12 or blade-body with high Carbon content by laser welding, made at their interface part 16 where the concentration of Iron additive with said very low percentage of Carbon is maximum.

According to a further advantageous feature of the invention, the blade-body 12 is provided with grooves 20 made on at least one of the faces of said body and extending vertically; preferably, as schematically shown in Figures 1 to 3, the grooves 20 are made on both opposite faces of the blade-body 12 where they are offset from each other. The grooves 20 have the function of allowing a better washing of the stone by the water which, during cutting, is appropriately conveyed and distributed, so as to ensure the correct cooling of said blade. Advantageously, the grooves 20 do not extend for the entire height of the blade-body 12, but limit their extension and stop near its lower edge 22; in this way, said blade- body 12 maintains the greatest thickness along the entire area intended to accommodate the sections (or sectors) or teeth 14, with the consequence that the latter can be bonded by laser welding at any point of said edge 22, i.e. without the need to identify a preferred portion. This is particularly useful, especially if there is a need to weld the sections (or sectors) 14 in such a position that they are close to each other and arranged, at least in part, in alignment with one or the other of the grooves 20. Advantageously, the sections (or sectors) or teeth 14 are bonded to the blade-body 12 in an offset manner, i.e. so as to alternately protrude into and out of the edge 22; this configuration allows the blade-body as a whole to follow a straight cut line, avoiding, among other things, the need to define a conical shape, as in the case of normal "gang saws" used for machining marble.

The possibility of bonding the sections (or sectors) or teeth 14 to the blade-body 12 perfectly with laser welding, given the fact that in their interface part 16 the concentration of iron integrates an extremely low carbon content and typically less than 0.1%, allows, in the first place, a more efficient weld than that obtainable by means of traditional brazing, thus creating an elastic modulus suitable for the correct and constant support of said sections (or sectors) and guarantees and, at the same time, a reserve of tenacity for the absorption of vibrations from the cutting of materials. Given these resistance characteristics, the blade as a whole can be advantageously limited in height to a height of between 60 and 130 mm, thus being significantly reduced in terms of size compared to traditional blades, with obvious advantages in terms of construction economies.

According to a further characteristic of the invention, the edge 22 of the blade-body 12 also performs a further function, cooperating with the lateral attachment fitting of the blade-body 12 to the machine frame (not illustrated); such attachment, for example of the type with sheets or caulked plates, is indicated by reference numeral 26 in figures 1, 5 and 6 which schematically represent it by way of example along a single head of said blade-body. Depending on the fact that the height of the blade-body 12, as specified above, can advantageously be limited to a height between 60 and 130 mm, in the connection to the respective attachments 26 said blade can be decentralized, so as to be fixed according to an arrangement that shifts it upwards, as shown in figure 5. This leads to the formation of the so-called "arrow", i.e., a counterforce that determines the creation of a downwardly oriented arch of the blade body 12 during its tensioning (figure 8) and thus facilitates the cutting of the material.

In fact, if the blade-body 12 were placed in the centre of the attachments 26, it would be tensioned in the same way at all points and would therefore have a constantly straight trend, as shown in figure 7 illustrating its conventional arrangement; if, on the other hand, the blade-body 12 is decentralized on the attachments 26, in accordance with figure 5 according to the invention, the forces change and lead it to assume a downward arch pattern to form the so-called "arrow" indicated in figure 8, with the consequent advantageous result that the sections (or sectors) or teeth 14 placed in the central part of said blade-body encounter the material to be cut before the others. The decentralized arrangement of the blade- body 12 with respect to the lateral attachments can be obtained with a dovetail type constraint, or by means of pins inserted in the through hole (s) 28 (one of which schematically shown in figure 1) that stabilize said attachments with respect to the machine frame. The arrows 30 shown in figures 5 and 6 schematically indicate the forces applied to the blade-body 12, which is tensioned by means of special hydraulic tensioners of the machine frame; said forces are generated by hydraulic systems such as cylinders and the like.

As may be seen from the above, the advantages which the invention achieves are evident.

In addition to the possibility of perfectly bonding the sections (or sectors) or teeth 14 with laser welding to the blade-body 12 and making said sections (or sectors) by free- sintering technology, which makes a diamond part weldable by laser technology, the provision of making grooves 20 with limited extension, in limited height on the blade-body 12 and interrupted near its lower edge 22, ensures that the latter constantly defines the longest thickness and in proximity to the entire area intended for laser welding bonding of the sections (or sectors) or teeth 14; furthermore, the fact that the teeth 14 protrude alternately towards the inside and outside of the lower edge 22 allows the blade-body 12 as a whole to more easily follow a straight trajectory during cutting. The limited height, which defines a lowered profile of the blade of the invention, also allows the blade to be decentralized with respect to the lateral supports 26, as well as to have available a disposable tool, with a weight lower than that of the prior blades; this allows the energy consumption of the multiblade machines during cutting operations and the costs for the disposal of said blades after use to be reduced. Despite the invention having been described above with reference to one of its possible embodiments, given solely by way of a non- limiting example, numerous modifications and variants will appear evident to a person skilled in the art in the light of the above description. The present invention therefore sets out to embrace all the modifications and variants which fall within the sphere and scope of the following claims.