Patent Description:
In the prior art many types of multi-wire frame for cutting blocks of stone material are known, said frames comprising multi-pulley rollers or multi-groove drums, inside the grooves of which diamond wires for cutting blocks of stone material into slabs slide.

In the present description reference will be made explicitly to multi-groove drums, it being understood that the principles of the present invention may be applied equally well also to a multi-wire frame with multi-pulley rollers, as will become clear from the continuation of the present description.

An example of a multi-wire frame is illustrated in <CIT> which describes a machine comprising two columns along each of which a slide supporting a multi-groove drum travels. The diamond wires travel over both the multi-groove drums, one of which is a motor-driven drum and the other one an idle transmission drum. The two multi-groove drums have large dimensions, in particular the diameter is greater than the height of the block to be cut.

The machine also has two multi-groove wire-guiding rollers or cylinders, each positioned in the vicinity of a multi-groove drum along the wire section which during machining is situated between the block to be cut and said multi-groove drum. The distance between the multi-groove wire-guiding drums is slightly greater than the maximum length of the blocks which can be sawn with the machine. The function of the wire-guiding rollers is that of keeping in alignment, parallel to each other, the diamond wires in the cutting zone, reacting to any transverse forces which tend to deviate the wires and preventing them from being displaced from the ideal trajectory; therefore the free section between the two wire-guiding rollers is only a few centimetres longer than the length of the block. Too large a distance between the wire-guiding rollers would affect the correct alignment of the wires during sawing of the blocks.

The multi-wire frames may also have other configurations, for example three small-size multi-groove drums may be envisaged, one drum located at the top vertex having not only a transmission function but also a wire-tensioning function so that the movement path of the wires preferably has a triangular configuration. There also exist frames with four small-size multi-groove drums located at the four corners of a rectangle, thus forming preferably a substantially rectangular movement path of the wires.

The machines of the prior art, although recognized as being valid, have a number of drawbacks and therefore do not always fully satisfy the user.

For example they have major limitations when it comes to cutting blocks of stone material with different dimensions.

As mentioned further above, if the distance between the wire-guiding rollers is slightly greater than the length of the block to be cut, the diamond wires are properly guided and during their cutting operation they maintain their straight position and consequently the cut is very precise.

If, however, the blocks have a length substantially smaller than the distance between the wire-guiding rollers, the latter will be located at a certain distance from the block to be cut so that there will be a section of diamond wire, of not insignificant length, situated between the wire-guiding rollers and the block. Along this path section, the wires will not be adequately guided and will have difficulty maintaining their straight position and, on the contrary, they may easily be displaced from their ideal arrangement. The cuts will therefore be much less precise compared to the situation previously described.

Therefore, in the case where blocks of varying length must be cut, not all the cuts will be performed in a precise manner. In particular, if blocks which have a length substantially smaller than the distance between the two wire-guiding rollers must be cut, the cuts will not be very precise.

One possible way of overcoming this drawback is to have two or more different-size machines each suitable for cutting a given range of lengths of the blocks, so as to be able to perform more precise cuts.

Obviously this solution is somewhat costly and requires a very large (open or closed) space able to accommodate several machines. Moreover, routine and extraordinary maintenance of the set of machines would become an extremely expensive item for the business activity concerned.

It is also evident that not even by providing several machines is it possible to have always the ideal distance between the wire-guiding rollers when there is a variation in the length of the blocks being machined.

It is for this reason that usually the most convenient solution is that of using a single cutting machine, accepting the fact that the cuts will not always be precise in the case where blocks which have a size substantially smaller than the distance between the two wire-guiding rollers must be cut. Both <CIT> and <CIT> discloses a multi-wire frame as per the preamble of claim <NUM>. Each of these documents discloses multi-groove wire guiding rollers which mutual distance is adjustable.

The object of the invention is therefore to solve the problems of the prior art.

A first task of the present invention is to provide a multi-wire frame in which it is easier to cut blocks of stone material of different sizes, performing cuts which are always very precise, even in the case of blocks with different lengths.

A further task of the present invention is to provide a multi-wire frame which is able to be adapted in an automatic and motorized manner to the length of the block to be cut.

The object and tasks are achieved with a multi-wire frame for cutting blocks of stone material according to claim <NUM>. Preferred embodiments are disclosed by the dependent claims.

The characteristic features and advantages of a multi-wire frame according to the present invention will become clear from the description below of possible embodiments, provided solely by way of a non-limiting explanation, with reference to the accompanying drawings, in which:.

<FIG> and <FIG> show a multi-wire frame according to the present invention denoted generally by the reference number <NUM>.

The multi-wire frame <NUM> for cutting blocks of stone material comprises two columns <NUM>, <NUM> each of which is provided with a slide <NUM>, <NUM> designed to move along the respective column <NUM>, <NUM>.

In accordance with a possible embodiment of the present invention, an upper cross-member <NUM> may be provided between the two columns <NUM>, <NUM> so as to connect together the two top ends of the columns <NUM>, <NUM> and reinforce the structure of the frame.

The slides <NUM>, <NUM> may be of the type known per se to person skilled in the art and are equipped with at least one multi-groove drum <NUM>, <NUM>, one of which is motor-driven, while the other ones are idle transmission drums.

As mentioned above, in this description, a multi-groove drum <NUM>, <NUM> is understood as meaning also a multi-pulley roller, for the sake of easier reference.

The multi-groove drums <NUM>, <NUM> are designed to engage with a plurality of cutting wires which extend relative to each other, over a plurality of grooves in a manner known per se to the person skilled in the art, and which therefore will not further described.

For easier reference, in the accompanying figures the multi-groove drums are shown in schematic form, with the first groove and last groove.

In accordance with a first embodiment of the present invention (not shown in the accompanying drawings), the multi-groove drums <NUM>, <NUM> are two in number, each provided on one of the slides <NUM>, <NUM>. Advantageously a pulley <NUM> is provided, said pulley not only having a transmission function, but also tensioning each diamond wire, thus creating a preferably substantially triangular movement path. The tensioning pulley <NUM> may be arranged on a cross-member <NUM> which joins together the two slides <NUM>, <NUM>.

In accordance with a further embodiment of the present invention (not shown in the accompanying drawings), the multi-groove drums may be four in number. Advantageously, each slide <NUM>, <NUM> may be provided with two multi-groove drums so that the four multi-groove rollers are positioned at the corners of a rectangle, this forming a preferably substantially rectangular movement path.

Although the cutting wire in the operating condition is moving, from the arrangement of the multi-groove drums <NUM>, <NUM> it is always possible to define a cutting section <NUM>. The cutting section, as can be clearly seen in <FIG>, is the section lying between the two multi-groove drums <NUM>, <NUM> which during operation exerts the cutting action on the block of stone material.

Wire-guiding rollers <NUM>, <NUM> are provided in the vicinity of each multi-grove drum <NUM>, <NUM>, along the cutting section <NUM>, said rollers being designed to guide the wires along the cutting section and withstand any horizontal/transverse forces which tend cause deviation of the cut from the ideal vertical path. The wire-guiding rollers <NUM>, <NUM> are provided with a series of grooves positioned so as to be able to seat the diamond wires. Advantageously, the positioning of the diamond wires may be varied depending on the desired thickness of the slabs to be cut, normally about one centimetre at a time starting from a minimum thickness of about <NUM> centimetres. Advantageously, they may have the same length as the multi-wire drums <NUM>, <NUM> so that their grooves correspond.

The multi-wire frame according to the present invention comprises movement means <NUM> for adjusting the distance between the wire-guiding rollers <NUM>, <NUM>.

The movement means <NUM> for adjusting the mutual distance between the wire-guiding rollers <NUM>, <NUM> comprise a mechanism <NUM> of the motor-driven type which allows the movement of at least one wire-guiding roller <NUM>, <NUM> towards or away from the respective multi-groove drum <NUM>, <NUM>.

In accordance with a first embodiment of the present invention, a wire-guiding roller <NUM>, <NUM> is provided with a mechanism <NUM> which allows the movement of a single wire-guiding roller <NUM>, <NUM> towards or away from the multi-groove drum <NUM>, <NUM>.

In accordance with an alternative embodiment of the present invention, both the wire-guiding rollers <NUM>, <NUM> are provided with a mechanism <NUM> which allows the movement of the wire-guiding roller <NUM>, <NUM> towards or away from the respective multi-groove drum <NUM>, <NUM>.

Advantageously the movement of the wire-guiding roller <NUM>, <NUM> occurs along a direction inclined downwards.

With reference to <FIG> and <FIG>, a possible embodiment of the mechanism <NUM> which allows the movement of the wire-guiding roller <NUM>, <NUM> towards or away from the multi-groove drum <NUM>, <NUM> will now be described.

Each mechanism <NUM> may comprise a support structure <NUM>. The support structure <NUM> may be fixed to the slide <NUM>, <NUM> or may be independent of the slide <NUM>, <NUM>. In accordance with a possible embodiment of the present invention, not shown in the accompanying figures, the support structure <NUM> may be arranged slidingly on the respective column <NUM>, <NUM> and be independent of the slide <NUM>, <NUM>.

In accordance with a possible embodiment of the present invention, the support structure <NUM> houses two bars <NUM> (in <FIG> and <FIG> only one bar can be seen) located on the two opposite sides of the wire-guiding roller <NUM>, <NUM>. The two bars <NUM> may have a circular cross-section. Advantageously, the two bars slide, by means of bushes or bearings <NUM>, inside corresponding cylindrical seats <NUM> provided in the support structure <NUM> and, at their ends, support the wire-guide roller <NUM>, <NUM>.

The two bars <NUM> may be arranged horizontally, i.e. in the longitudinal direction.

In this description, the term "longitudinal" is understood as meaning a direction parallel to the plane which contains the direction of the two columns, and substantially perpendicular to the direction of movement of the slides on the columns.

Advantageously, the two bars <NUM> may be inclined a few degrees downwards so that, when the bars <NUM> are extracted, the angle of tangency of the wire with the wire-guiding roller remains constant and thus the winding arc also remains constant.

The bars are provided with a rack <NUM>. The rack <NUM> may be arranged directed downwards. In accordance with a possible embodiment of the present invention, each bar may be provided with a seat for a rack which may be removable, for example by means of screws, or fixed in a non-removable manner.

The rack is designed to mesh with a pinion <NUM> operated by a gear motor <NUM>; it should also be noted that the rack <NUM> may also act as an anti-rotation element for the bar.

In accordance with a first embodiment of the present invention, the gear motor <NUM> is arranged on the support structure <NUM>, as in the embodiments shown in the accompanying figures.

In accordance with an alternative embodiment of the present invention, the gear motor <NUM> may be arranged on a structure independent of the slide and designed to be displaced along the column.

The gear motors <NUM> are two in number for each wire-guiding roller <NUM>, <NUM>, each of them with its own pinion <NUM> acting on a respective rack <NUM>. The gear motors <NUM> of each wire-guiding roller <NUM>, <NUM> are operated in synchronism so that the axis of the wire-guiding roller during the displacement always remains parallel to itself.

In accordance with the embodiment in which both the wire-guiding rollers <NUM>, <NUM> are designed to move, all four gear motors <NUM> are designed to be operated in pairs in synchronism.

When the gear motors are operated, the associated pinions rotate and move the respective racks and therefore the bars in one direction or the other.

A support bracket <NUM> for the wire-guiding roller <NUM>, <NUM> may be mounted at the free end of each bar <NUM>.

In accordance with a possible embodiment of the present invention, two supports <NUM> may be mounted at the bottom end of the bracket <NUM>, preferably in an pivoting manner about a vertical axis, said supports each having a cylindrical seat <NUM> inside which the two ends of the spindle <NUM> which rotatably supports the wire-guiding roller <NUM>, <NUM> are inserted.

In accordance with a possible embodiment of the present invention the pivoting support may be provided with pins <NUM>, <NUM> in the vertical direction, designed to be engaged with respective seats <NUM>, <NUM> formed on the bottom end of the bracket <NUM> and corresponding seats formed on the support <NUM>, as shown in <FIG>.

Each of the two ends of the spindle about which the wire-guiding roller rotates is inserted in a pivoting support. It is preferable for the support to be pivoting since, owing to the intrinsic elasticity of the system, the movement of the wire-guiding rollers might not be perfectly synchronous and therefore there is the possibility that a bar may project more than the other bar, preventing or hindering the movement of the wire-guiding rollers. Therefore, in order to avoid problems arising from imperfect synchronism, the end pins of each roller are able to pivot about a substantially vertical axis and a substantially horizontal axis.

In the configuration shown in <FIG>, the two bars and therefore the wire-guiding roller are fully retracted towards the outside of the frame, while in <FIG> the two bars and therefore the wire-guiding roller are fully extended towards the inside of the frame.

In the first condition the frame is able to cut blocks with the maximum permitted size (length), while in the second position the frame is able to cut blocks with the minimum permitted size (length).

In accordance with a first embodiment of the present invention, the block of stone material which must be cut is positioned in the centre of the multi-wire frame, and both the wire-guiding rollers are both operated in a symmetrical manner such as to move closer together or away from each other.

The two wire-guiding rollers are moved depending on the length and position of the block to be cut and, in particular, are moved so as to be positioned as close as possible to the block. It is possible to provide automated systems equipped with detection means, for example detectors/transducers (encoders) of the type known per se to the person skilled in the art and designed to detect the length and position of the block, and a control unit integrated in the machine and designed to set automatically the distance of the wire-guiding rollers from the block to be cut.

The advantages of the present invention compared to the multi-wire frames of the prior art are therefore evident.

Firstly it is possible to predispose the multi-wire frame in such a way that it is fully adaptable to any size and position of the block to be cut. The diamond wires are guided perfectly and maintain their ideal straight position so that the cut performed will be very precise.

It is thus possible, when there is a variation in the length and position of the block to be cut, to position the two wire-guiding rollers in the position closest to the block to be cut and therefore manage to keep the diamond wires as straight as possible, obtaining very precise cuts.

Claim 1:
Multi-wire frame (<NUM>) for cutting blocks of stone material, comprising two columns (<NUM>, <NUM>) each of which is provided with a slide (<NUM>, <NUM>) designed to move along the respective column (<NUM>, <NUM>),
each slide (<NUM>, <NUM>) being provided with at least one multi-groove drum (<NUM>, <NUM>) designed to engage with a plurality of cutting wires between the two slides (<NUM>, <NUM>);
said multi-wire frame (<NUM>) being provided with two multi-groove wire-guiding rollers (<NUM>, <NUM>) which are designed to guide the wires along the cutting section;
characterized in that the multi-wire frame (<NUM>) comprises movement means (<NUM>) for adjusting the distance between the multi-groove wire-guiding rollers (<NUM>, <NUM>); and
in that the movement means (<NUM>) are of the motorized type and comprise a mechanism (<NUM>) of the motor-driven type which allows the movement of at least one of said multi-groove wire-guiding rollers (<NUM>, <NUM>) towards or away the respective multi-groove drum (<NUM>, <NUM>), at least one of said multi-groove wire-guiding rollers (<NUM>, <NUM>) being provided with the motor-driven mechanism (<NUM>);
there being provided a pair of gear motors (<NUM>) for each multi-groove wire-guiding roller (<NUM>, <NUM>) with its own pinion (<NUM>) acting on a respective rack (<NUM>), the gear motors (<NUM>) of each multi-groove wire-guiding roller (<NUM>, <NUM>) being operated in synchronism so that the axis of the wire-guiding roller during the displacement always remains parallel to itself.