WO2005108029A2

WO2005108029A2 - Vertical-type machine for machining marble, granite, or the like

Info

Publication number: WO2005108029A2
Application number: PCT/IT2005/000264
Authority: WO
Inventors: Franco Pavoni
Original assignee: Franco Pavoni
Priority date: 2004-05-06
Filing date: 2005-05-05
Publication date: 2005-11-17
Also published as: ITRM20040070U1; WO2005108029A3

Abstract

A machine, or a machining center, with numeric control (N/C), used for machining marble, granite, or any other ornamental stone, comprising a support structure and an assembly of controlled axes (X, Y, Z) for controlling the movements of one or more cutting tools which are mounted on one or more machining heads (9), said support structure supporting an inclined plane (5) which sustains a workpiece of marble, granite, or the like.

Description

A vertical-type machine for machining marble, granite, or the like

Technical Field

The present invention relates to numeric control (N/C) machines and preferably those with three or more controlled axes, generally used for processing workpieces of marble, granite or the like, and particularly slabs made of such materials, especially to make straight and shaped cuts, incisions, a high relief, a bas-relief, sculptures, etc.

Background Art

Those skilled in the art already know N/C machines (machining centres) for processing marble slabs or the like. In these machines the slab (or generally the workpiece) is laid on a perfectly horizontal plane formed by the machine, which acts as a support during the machining. The movements of the axes are controlled with a specific software and during processing the cutting tool is continuously lubricated by means of water jets directed towards the tool and ejected from nozzles mounted on the machining head together with the tool. The reason for lubrication is to reduce temperature increase of the tool, caused by friction between tool and workpiece, wherein water penetrates at a predetermined pressure between the grains of abrasive material which form the tool. Normally these grains are made of diamond, and the tool may for instance be obtained by sintering or by means of an electrolytic process. Moreover, there exist various kinds of tools, e.g. those used for roughing and those used for finishing works, but in this patent application no limitation is made with regard to any particular kind of tool. Some tools, usually those used for roughing, are themselves internally traversed by a duct for the passage of the lubrication water. A problem related to lubrication resides in the fact that the diamond grains detach themselves or are subject to rapid wear if water cannot reach all gaps existing between them. Unfortunately, in known machines a good lubrication cannot always be guaranteed because quite often the tool happens to be immersed in water during the machining process. One may mention for example the case of a bas-relief to be the carried out on a marble slab which is laid on the horizontal working plane of the machine, in which case the bas-relief is effected within a frame formed on the slab itself. In this situation the inventor has observed that the working tool generated a whirl, because of its rotation, in the water that stagnated inside all or almost all the region of the slab bounded by said frame. This whirl, which is created by the diamond grains or chips that protrude from the tool surface and act like the "blades of a rotor", prevents the cooling water - which is continuously sprayed by said nozzles - from reaching the gaps between the individual grains. Further, it should be noted that the intensity (force) of the water jets will in any case be reduced by the water which stagnates and surrounds the tool, and this, in turn, is an additional effect that lowers the lubrication efficiency. Therefore, summing up, in conventional machines the cutting tool must be replaced frequently also because of this drawback preventing the water jets to directly reach the working tool.

A second problem of the machines of the prior art, which has been recognised by the inventor of the present patent application during several tests, is that marble particles produced during the machining accumulate on the slab surface and are not removed therefrom. Thus, these particles will be "ground once again" by the tool during its various passages, and this, in turn, leads to the obvious result that the diamond of the cutting tool is subject to an increased wear. This second problem associated with traditional machines immediately leads to another problem which is directly linked thereto. As a matter of fact, the mire formed by the water and the fine powder of material removed during the machining, remains also on the supporting plane; normally, the latter, while maintaining a perfect horizontal position of the workpiece, is not perfectly smooth, but has a plurality of recesses and ribs, so that the mire will adhere thereto and will harden, thereby forming deposits (encrusting) that are difficult to remove especially in the spaces between the recesses and ribs. Therefore, a noticeable loss of time will result when cleaning the machine. By observing the operation of the machines belonging to the prior art, the present inventor has also ascertained the existence of many other drawbacks. A relatively small machine, having a lateral extension (size) of e.g. 2 metres, implies a total "effective size" of about 4 meters, which is due to the fact that the slab must be horizontally introduced in the machine when it is loaded (laid) on the horizontal processing plane. This effective size (given by the sum of the real dimensions of the machine and of the space needed to load the slab),may sometimes be too large especially if the machine is to be sold to small workshops of artisans who are among the main customers for this type of product. Moreover, the slab loading operation implies a certain effort for the operator, who is forced to bend down and strain his back. Consequently, it is desirable to realise a machine which is simpler to use for the final operator or user.

It is also advantageous to improve the convenience and practicality of use of the machine for the operator when he carries out the replacement of the tools. In fact, during replacement of the tools or of a single tool in a conventional machine, the operator is forced to perform a twisting movement and a simultaneous bending of his back because the working head is located at a small height with respect to the ground. It has also been noticed, in case of a workpiece formed by a slab, that the latter is subjected to noticeable vibrations due to the load stresses of the cutting tool during the processing. Actually, the horizontal arrangement of the slab promotes its flexural vibrations, and this implies greater noise and increased wear of the tool which is in contact with the slab surface; the time consumed for the processing also increases in consequence of this.

A further drawback of horizontal, conventional machines used for the machining of marble slabs is that they have long periods during which the production is stopped. After completion of the processing phase, the scraps must be carried out of the processing plane (machining plane) and the various machined pieces must be taken out by one or more operators. Only after this latter step - corresponding to a period of inactivity or "idle time"- is terminated, one or more new slabs can be manually loaded on the working (processing) plane.

This drawback of the prior art machines will be removed by a special embodiment of the present invention, involving a completely automatic system for: a) loading and unloading the slab (along an inclined vertical plane), in a totally automatic manner; b) automatically holding (locking) the slab(s) during its (their) machining; c) automatically unlocking the slab(s) at the end of its (their) machining; d) automatically discharging the scraps during the machining and before the automatic discharge of the machined pieces. Therefore, the object of the present invention is to realise a numeric control (N/C) machine, having for instance one or more controlled axes, allowing to perform the most diverse machining operations on a workpiece of marble, granite, or the like, e.g. on a slab, by eliminating all aforementioned disadvantages of conventional machines that generally belong to this typology. The term "machining operation", in this context, includes for example to the following operations (carried out by a specific program): pattern obtained with rectilinear or shaped cuts, incisions, scratch works, bores for character insertion, bas- relief, high relief, various kinds of milling operations, tridimensional sculptures, etc. These are obviously non exhaustive examples. In this respect the machine of the present invention does not differ from conventional ones.

Another problem to be solved by the present invention is that of protecting in a more adequate manner from impurities (dust, etc.) the mechanical parts which are associated to the N/C controlled axes and which are lodged inside respective metallic section bars or channels, this protection being obtained in the background art by employing the usual PNC or cloth-made bellows of traditional machines.

Disclosure of invention The present invention solves the above mentioned, specific drawbacks, relating to the machining of marble, granite or the like, by means of the features defined in claim 1. According to the invention, the support plane of the marble slab is mounted in an inclined manner on the support structure (support frame) of the machine, so as to constantly maintain the surface of the slab free of water and mire; in fact, the latter drain by gravity towards the lowest point of the support plane and are conveyed from this point towards decantation tanks or basins.

Moreover, the support plane will always be clean and "washed", since its surface will be free of water and mire at the end of the machining. It should be noted that the present invention is generally applicable to the processing, by means of a machining center with electronic pantograph, of several materials including composite materials and specifically those which give rise to a noticeable amount of rubbish during the machining and which could therefore result in a greater wear of the cutting tool (effect of "chopping" or "grinding" the rubbish).

Brief Description of Drawings

The present invention will now be illustrated in more detail with reference to two possible embodiments thereof, which are neither binding nor limitative, and are shown in the attached drawings, in which:

Fig. 1 is a lateral view of the machine, or numeric control (Ν/C) machining center, according to the first embodiment of the invention;

Fig. 2 is a plan view from above of the machine shown in Fig. 1 ; Fig. 3 is a front view in the direction of the arrow A in Fig. 1 ;

Fig. 4 is the B-B cross section defined in Fig. 1 , and finally

Fig. 5 is an axonometric view of the machine according to the first embodiment;

Fig. 6 is a front view of the machine according to the second embodiment of the present invention;

Fig. 7 is a lateral view of the machine of Fig. 6.

Description of Preferred Embodiments of the Invention

First of all, with reference to figures 1 to 5, a description will be given of the first embodiment of a vertical-type machine employed for machining marble, granite, or the like, according to the present invention.

The machine according to the present, non-binding embodiment, used for processing marble, granite, or the like, is an N/C electronic pantograph with three or more controlled axes. It comprises four vertical, (tubular) section bars 1, 1, 1', 1 ' interconnected by steel-made, horizontal (tubular) section bars 2. The four feet 7 are welded, for instance, to the vertical section bars 1 and 1 '. The two vertical section bars 1 ' located on the rear part of the machine have a length exceeding the length of the two vertical section bars 1 located on the front side. Two oblique longitudinal members 3, 3 respectively join to each other the two upper ends of two tubular, vertical section bars 1, 1', located on the same side of the machine. The two oblique longitudinal members 3 are interconnected by two horizontal longitudinal members 4 that are spaced apart one form the other (in the embodiment these are formed by sheet metal tubes made of steel with square cross-section). The horizontal longitudinal members 4 form support means for the inclined plane 5 which supports the workpiece (the latter is not shown). The inclined, support plane 5, actually extends up to the two longitudinal members 3 (even if this is not illustrated in the figures), and it forms the "bottom" of a basin used for the machining operations. Two longitudinal structural components, or section bars 6, are attached to the upper side of the oblique longitudinal members 3, and they contain the driving mechanisms of the machining head (working head), used to displace the latter in the direction of the "Y axis". The section bars 6 are open on their upper, free side (not in contact with the longitudinal members 3), although they are protected on this side by means of movable bands that replace the usual bellows of conventional machines. In other words, the movable crosspiece 8 which supports the machining head 9, may move "vertically" (direction of axis "Y") along the structural components 6, and to both ends 10 of the crosspiece there are fixed respective PVC bands 11 which slide inside two lateral guides and cover the upper, open part, of the section bars 6, in order to prevent an infiltration of dust or impurities of various kinds. Even if not shown in the drawings, at the points indicated by 12 (Fig. 3), that is, at the opposite ends of the components 6, there are provided four respective roll-up rollers suited to roll up or unroll the two bands 11, 11 during the movements of the crosspiece 8. This system is capable of preventing in a much more effective way than traditional bellows the infiltration of dust or impurities towards the inner part of the section bars 6, where the drive members of the crosspiece 8 are located, because said bellows could not form a barrier against dust etc. at the points between their folds. A similar system including rolling-up rollers and PNC-made protection bands movable between lateral guides is also provided on the movable crosspiece 8 itself, in place of traditional bellows, to prevent impurities from reaching the drive mechanisms of the machining head 9 used to drive the latter in the horizontal direction (controlled axis "X"). Also the drive mechanisms for the Z-axis are protected by the same system. The machining head 9, as already known to those skilled in the art, includes on its lower side (not visible in Fig.5 and in Figs. 1-4), at least one cutting tool, and one or more nozzles used to spray (eject) the cooling water towards (this) these tool(s). The latter are usually formed by abrasive grains of diamond, on their surface which is in contact with the workpiece. The present invention is clearly neither limited to a specific tool type (as one used for roughing, finishing, etc.), nor to a particular tool obtained by means of a specific manufacturing process (electrolytic process, sintering process, etc.), moreover, it is not limited either to a tool which possibly has an internal lubrication duct; instead, it has a general character. The cutting tool is also displaced during the machining process in the orthogonal direction relative to the inclined support plane 5 (direction of controlled axis "Z"), using suitable means (not shown) provided on the head 9, in order to perform more or less deep incisions on the workpiece while the latter rests on the support plane 5, which, in turn, is fixed to the horizontal longitudinal members 4. The support plane 5 is advantageously formed of "staves" of anodised aluminium having parallel grooves and ribs, as shown in the figures. As opposed to conventional machining centers, which carry out the machining process on a horizontal support plane of the workpiece, the machine of the present invention has an inclined support plane 5. The advantages resulting from this solution are innumerable, since it becomes possible to overcome all drawbacks of the background art that were mentioned in the first part of the description. During the machining, the water and the mire (= water mixed with dust/powder formed by the removed material) descend under the effect of gravity along the inclined plane 5 and reach the lower part of the "basin". The latter is bounded by a flange (not shown) which extends (horizontally) between the lower ends of the oblique longitudinal members 3 and which collects the water and mire in the lowest region of the basin. Some holes machined into said flange cause these materials to fall into decantation receptacles belonging to a recirculating system used to separate the mire from the already used water, the latter being then recirculated and sprayed (ejected) through the nozzles (and/or through a possible inner lubrication duct of the tool). In this manner the mire and the water will neither remain on the marble slab nor on the inclined support plane 5; this implies a reduced tool wear and at least a 30% gain in terms of the average cutting tool life. The increased duration of tool life is due to three main factors: - there is no stagnating water any more on the marble slab (or the like), particularly during the execution of a bas-relief, so that the lubrication water jets ejected by the nozzles can directly "hit" the tool which is no more immersed in the stagnating water;

- the rubbish or powder formed by the already removed material does not stay on the slab surface and so it is not ground (chopped) again during the successive passages of the cutting tool tip, instead, it gets mixed with the water sprayed from the nozzles and is drawn away, downwards, until it reaches the lower collecting flange;

- the vibrations of the slab are reduced with respect to a slab laid on a horizontal support plane, as was demonstrated in several tests, and as may also be intuitively deduced from the fact that the lower side of the slab (on which part of the whole weight of the slab rests) behaves as if it was subject to a mechanical constraint; therefore, the reduced vibrations prolong the life of the tool in contact with the slab surface, and they allow a greater machining speed. Moreover, several other advantages result from this particular structure of the machine according to the present invention. As concerns cleanliness, the support plane 5 will always remain "washed" and clean, as opposed to the horizontal plane of conventional machines, since the mire descends by gravity along the inclined plane 5. With regard to the overall space required, if an illustrative and non-binding comparison is made with a conventional machine of about 4 m effective size (defined as the space required for loading the slab summed to the actual horizontal dimensions of the machine), then, a model of machine according to the present invention allows to process marble slabs or the like having the same size but with only 2 m (2 meters) of overall effective horizontal size. Since the machining head 9 in the "vertical" machine according to the present invention is located at a greater height (above the ground) with respect to that of "horizontal" machines of the prior art, the operator does not need to bend his back and/or twist it, in order to replace the cutting tools of the machining head 9. Even the loading of the slab is facilitated considerably since it won't be necessary to bend down because the slab can simply be laid on appropriate supports fixed to the inclined plane, by positioning the slab vertically on the inclined plane, according to the normal handling procedures (transport) in the vertical condition of said slabs. Preferably, at least all those tubular structural elements that will be in direct contact with the water and the mire, will first be sandblasted and then hot-galvanised. Other machine parts may be formed e.g. of PNC. The plane 5 may be formed by anodised aluminium staves (shaped sections).

It should be noted that in the description and in the drawings all those details as are already known or intuitive for a skilled person, and/or as are already included in traditional machines, have been omitted for simplicity. For example, in the drawings, the operator's console for controlling and inputting data in order to programme the movements of the three controlled axes, has been omitted. Moreover, the lower part of the machining head (working head) has not been shown, because this already belongs to the common general knowledge. All hoses (flexible tubes) used to feed water to the nozzles, the decantation receptacles, the water recirculating system

(pump, etc.), have been omitted from the drawings too. The machine could possibly be operated without any water recirculating system, that is by continuously feeding a water flow 'from outside'. All such details do not, however, modify the general concept underlying the present invention. The machine of the present invention has the noticeable merit of limiting the overall space required during its transport (it is no more necessary to disassemble parts of the machine in order to pass through narrow main doors, in contrast to conventional machines that required this partial disassembling). The overall size is reduced also during the operation of the machine, because, as may be seen from Fig. 1, the head 9 almost always remains, during the machining, inside the outer profile (contour) of the machine; in other words it does not excessively project beyond the front vertical section bars 1 , even when it reaches the lowest region of its "vertical" stroke. Also of particular relevance is the fact that the center of gravity of the machine always remains within its "pressure or weight profile" which is defined by the area bounded by the feet 7.

The machine according to the present invention may in particular be advantageously applied in the field of marble or granite sculpture, or sculpture of similar materials, for instance in the funerary art (tombstones, etc.) or to realise home furnishing (interior decoration) (for instance top parts of washbasins for kitchens and bathrooms).

The present invention (with regard to its first embodiment shown in Figs. 1-5) has been described above in a somewhat detailed manner in order to allow a skilled person to easily and directly understand how the invention may be put into practice to attain the above objects. Actually, some means may be replaced by other, technically equivalent means, without altering the present general inventive concept, that has been clearly outlined in the present document. Finally, it should be noted that the disclosed machine could be used - obviously - in combination with other ones which perform other "tasks", so as to form part of a machining center which is even more complex. Moreover, means could be provided which are suited to adjust the inclination (slope) of the support plane (5), according to the requirements of the operator. Referring now to Figs. 6 and 7, a description will be given of the second embodiment of a vertical-type machine according to the present invention, used for machining marble, granite, or the like. The application fields are substantially the same as those of the first embodiment (Figs. 1 to 5), e.g. the production of top parts of washbasins for bathrooms, but further advantages are achieved in respect of productivity (elimination of idle time (down time)). In the description of this second embodiment, all details related to the machining head, the tools mounted on the same, the lubrication system employing water, etc., which either form part of the known art or are essentially the same as those of the first embodiment, will be omitted from the discussion in order to avoid repetitions. The description will focus instead solely on those features which specifically concern the second embodiment and which serve to increase the productivity and to render the process substantially "continuous" (with no machine idle time). Note that in Fig. 6 the pantograph with controlled axes and the respective machining head 9 have been omitted from the drawing, in order to better emphasise the improvements with respect to Figs. 1-5 (however these parts are shown in Fig. 7; see also reference 109).

Substantially, the differences with respect to the first embodiment are as follows (the reference numbers of the second embodiment are increased by 100 units with respect to those of the first embodiment).

Laterally, on the right and left hand side of the machine proper 100, there are provided conveyor belts 120, 120' used for the loading and unloading operations, which are associated to a respective series of displacement rollers 121, 121 '. The planes formed by these belts 120, 120' with their corresponding displacement rollers 121, 121' that internally support the belts themselves, have the same inclination as the "inclined plane used for the machining operations" which is included in the machine proper 100.

On the lower side of the slab 123 (or respectively of the finished workpiece 123'), on the right (or left) side of the machine 100, there are provided several rollers 122 (or respectively 122') used for the support and loading (or respectively the unloading) of the slab 123 to be processed (or respectively the finished workpiece 123'). A slab to be processed 123 is carried towards the machine 100 in the direction of the arrows F], and then, at the end of the machining operation, it is discharged, always with the same vertical tilt, to the left side of Fig. 6, as indicated by the arrows F ; in this region, the "machined slab" 123', or rather the finished wokpiece (finished product) 123', is supported on the motorised rollers or belts 122', and, on a plane surface, on the unloading conveyor belt 120' and its displacement rollers 121 '. To be introduced inside the machine proper 100 which carries out the machining operation, the slab 123 must pass through an elongate aperture 124 (Fig. 7) which was absent in the first embodiment (see Fig. 1). A similar slot 124 will be provided on the left side of the machine proper 100, shown in Fig. 6, in order to discharge the finished product 123'. In the first embodiment the inclined plane used for the machining operation was formed by the inclined support plane 5. In the present embodiment, the "inclined support plane", or plane used for the machining, will be formed for instance by three movable boards 105', 105", 105'", which can be moved along the three horizontal, longitudinal members 104', 104", 104'", in the direction indicated by the arrows Fi (F₂) or in the opposite direction, either manually or automatically (ratio-motor).

The three "vertical" boards 105', 105", 105'", are inclined according to the machine plane, in the same way as the inclined support plane 5 of the first embodiment. On the boards 105'-105'" there are provided the following means: a) movable suction cups 125 capable of temporarily fix a slab to be machined; b) lower, driven support rollers, 126, which may be retractable, and which are apt to hold, along its lower edge, the slab 123 of marble or the like which is fed from the loading system; c) small rollers 127 (that may all be idle, motorised or mixed) that are retractable and capable of jutting out some millimeters (in the advanced position) from the plane defined by the suction cups 125 (in Fig. 6 there are six such retractable support rollers 127 (at least one for each suction cup) arranged in couples on each "vertical" board 105', 105", 105"').

The advancement (protrusion) and the retraction of these small rollers 127 may be for instance pneumatically controlled, like the (possible and analogous) advancement and retraction movements of the lower, driven small support rollers 126 of the slab lower edge; a) vertical guides on the boards 105', 105", 105'", allowing to decide which position is to be occupied by the suction cups 125 along these boards 105' etc. before beginning the machining of the slabs 123, so as to be able to manufacture a series of identical finished products 123' (for example top parts of bathroom washbasins or kitchen sinks). It should be noted that these guides for the suction cups 125 are not shown in Fig.6. The work cycle is as follows:

An operator loads several slabs 123 on the loading belt 120 which has the same inclination as the machine plane (plane used during machining) and is supported by the displacement rollers 121. The slab 123 which is located leftmost will be introduced first into the machining center 100, by the motorised rollers or belts 122 and by the motorised loading belt. The rollers 122 support the slab 123 along its lower edge and shift the same towards the machine proper 100 where the machining is to be carried out. At this time it will be supported by the other rollers, 126, and it will be stopped at a predetermined position on the inclined boards 105', 105", 105'", as a consequence of the command from a photocell or the like. The (rubber-made) suction cups will not be damaged by the slab 123 since the small rollers 127 now project (see above) by some millimetres from the plane of the suction cups 125.

Then, the small rollers 127 are actuated (retracted in the orthogonal direction with respect to the inclined plane defined by the boards 105' etc.) and thereafter the board is held firmly by the suction cups 125.

Also the lower, support rollers 126 may be actuated (retracted) (the force exerted by the suction cups 125 is sufficient to hold the slab 123), in case it is desired to machine the lower edge as well, or for other reasons. At the end of the machining operation, the rollers 127 (and possibly the rollers 126, provided they are not already in the advanced position (see above)) are brought in the advanced position and are rotated in order to unload the machined slab 123' in the F₂ -direction, towards the unloading system 120' of this finished workpiece 123'. It should be noted that since the "inclined plane" of this second embodiment of the invention has several openings formed between the boards 105', 105", 105'" and between the horizontal longitudinal members 104', 104", 104'", the scraps can fall on the chutes 128 and are collected by the collection container 129 of the scraps (Fig. 7). Several modifications can be made to the second embodiment of the present invention since the above description is to be considered only illustrative.

For example, a system similar to that of the belts 120, 120' could also be present in the central, machining part 100 of the machine, and could be shifted downwards (after the slab 123 has been loaded on the inclined plane used for the machining operation) in order to clear the way for the system of boards 105', etc., which in that case should also be movable in the orthogonal direction with respect to the machine plane. The importance of the present invention with regard to this second embodiment is emphasised once again.

After the machining there are no idle times, because the slab(s) is (are) unloaded on the left hand side while the scraps have been unloaded on the rear part of the machine. Therefore, the machine may be watched by a single operator who loads the slabs 123 and unloads the machined workpieces (finished products) 123'; apart from that, the operation is carried out automatically. In contrast with prior art machines of the horizontal kind, the machined workpieces do not need to be removed manually or to be separated from the scraps by climbing on the horizontal machine plane and stopping the operation of the machine during this period of time.

Moreover, as in the first embodiment it is not necessary to clean - or at least to clean frequently - the machine plane, unlike what happens for a horizontal plane of the prior art.

Claims

1. A machine, or a machining center, with numeric control (N/C), used for the machining of marble, granite, or any other ornamental stone, comprising a support structure (1,1'; 101, 101'; 2, 2'; 102; 3) and an assembly of controlled axes for the displacement of one or more tools mounted on one or more machining heads (9; 109), characterised in that said support structure supports an inclined plane (5; 105'; 105"; 105'") used to hold a workpiece made of marble, granite, or the like.

2. A machine or machining center according to claim 1, wherein said machining head (9; 109) supports one or more nozzles which eject a lubrication liquid towards a tool.

3. A machine, or a machining center, according to claim 1 or 2, wherein at least one tool has an inner passage traversed by a lubrication liquid.

4. A machine, or a machining center according to any of the preceding claims, wherein the machining is performed along three or more controlled axes (X, Y,Z).

5. A machine, or a machining center, according to anyone of the preceding claims, wherein said inclined, support plane (5) forms the bottom of a basin in whose lowest region the lubrication liquid is collected together with the mire formed by the lubrication liquid mixed to the rubbish consisting of the material removed from the workpiece during the machining.

6. A machine, or a machining center, according to anyone of the preceding claims, wherein there are provided means for separating the lubrication liquid from the mire.

7. A machine, or a machining center, according to claim 6, wherein means are also provided to recirculate, that is to reuse, the lubrication liquid that has already been separated from the mire.

8. A machine, or a machining center, according to anyone of the preceding claims, wherein at least those parts that are in contact, or could get in contact with the mire or other corrosive substances, are subjected to an anticorrosion treatment in order to resist to corrosion, or else are formed by a material which cannot be consumed by corrosion.

9. A machine, or a machining center, according to anyone of the preceding claims, wherein the traditional bellows for the protection from impurities of the mechanisms that control the movements of the controlled axes, are replaced by bands or ribbons (11) which slide inside lateral guides, and by respective takeup/unwinding rollers to wind up/unwind these bands.

10. A machine, or a machining center, according to anyone of the preceding claims, wherein there are provided means for adjusting the inclination of the inclined support plane (5; 105'; 105"; 105'"), and for locking it in a desired inclined position.

11. A machine according to anyone of the preceding claims except claim 5, further comprising:

- at least a system for laterally loading the slabs (123) of marble, granite, or the like, said lateral loading system (120, 121, 122) having an inclined plane with substantially the same inclination as the machining plane proper; - at least a system (120';121 ';122') for laterally unloading the machined workpieces (123') and arranged on the opposite side of the inclined, machining plane, and again having substantially the same inclination as the machining plane; wherein, in this case, the machining plane (105'; 105"; 105'") is formed of one or more boards (105'; 105"; 105'") whose positions are preferably adjustable along longitudinal members (104', 104", 104'") depending on the kind of machining process to be carried out; openings being provided between the boards (105'; 105"; 105'") and the longitudinal horizontal members (104'; 104"; 104'") in order to discharge the machining scraps on the rear side of the machining plane (105'; 105"; 105'"); first support and lateral advancement means (126) being also provided to support the slab (123) at least before and after the machining operation and during the loading/ unloading of the slab (123) on/from said machining plane.

12. A machine according to claim 11, wherein there are provided locking means (125) for firmly holding the slab (123) during the machining operation, said means acting on its rear side directed towards the rear side of the machine.

13. A machine according to claim 12, wherein said locking means (125) are mounted on said boards (105'; 105"; 105'").

14. A machine according to claim 12 or 13, wherein said locking means consist of suction cups (125).

15. A machine according to claim 13 or 14, wherein said locking means (125) have an adjustable position along guides which are provided on said boards (105'; 105"; 105'").

16. A machine according to anyone of the preceding claims, wherein there are provided further support and lateral advancement means (127) for supporting and laterally advancing the slab (123) and the machined workpiece (123') with respect and along the inclined, machining plane (105'; 105", 105'"), said means being formed by retractable shift rollers (127) preferably arranged on said boards (105'; 105"; 105'"), these shift rollers defining an inclined, ideal plane in their position corresponding to their maximum jutting out, this plane being parallel to that defined by the locking means (125) and being spaced apart from it by some mm.

17. A machine according to claim 11, wherein said first support and lateral advancement means (126) for supporting and laterally advancing the slab (123), or the machined workpiece (123'), on the machining plane (105'; 105"; 105'"), are themselves retractable.

18. A machine according to anyone of the preceding claims, wherein the lateral loading system (120, 121, 122) of the slab (123) includes motorised rollers (122) which support the slab along its lower edge.

19. A machine according to anyone of the preceding claims, wherein the lateral unloading system (120', 121', 122') of the machined workpiece (123') includes motorised rollers (122') which support the slab along its lower edge.

20. A machine according to claims 18 and 19, wherein said loading and unloading systems include inclined conveyor belts with inner shift rollers (121, 121').

21. Use of a machine according to anyone of the preceding claims 1 to 20, for the manufacturing of top parts of washbasins, sinks, or for producing memorial tablets or tombstones, or similar objects obtained from machining workpieces of marble, granite, and in particular slabs of marble, granite or the like.