EP0980740A2

EP0980740A2 - Machine for stone surface treatment, particularly for slabs made of stone or similar, such as marbles, granites, but also ceramics and other building materials, used for flooring and lining

Info

Publication number: EP0980740A2
Application number: EP99115671A
Authority: EP
Inventors: Federico Benetti; Barnes C/O Benetti Ken
Original assignee: Benetti Meyers International Srl
Current assignee: Benetti Meyers International Srl
Priority date: 1998-08-20
Filing date: 1999-08-09
Publication date: 2000-02-23
Anticipated expiration: 2019-08-09
Also published as: ITSV980046A0; IT1305414B1; ITSV980046A1; EP0980740B1; DE69922095T2; ES2234191T3; EP0980740A3; ATE283145T1; DE69922095D1

Abstract

A machine for stone surface treatment, particularly for slabs made of stone or similar, such as marbles, granites, but also ceramics and other building materials used for flooring and lining, which comprises means (2, 2', 2'', 10, 8, 8', 13, 13') for grinding and/or polishing and/or shaping rims or edges and means (1) for conveying workpieces (P) to said grinding and/or polishing and/or shaping means (2, 2', 2'', 10, 8, 8', 13, 13') According to the invention, said machine comprises at least one grinding and/or polishing and/or shaping tool, consisting of a plurality of grinding and/or polishing and/or shaping members (402, 310) which are mounted on annular conveyors, having the form of a rotatably driven continuous band, chain or belt (2, 2', 2'', 10, 8', 13').

Description

The invention relates to a machine for stone surface treatment, particularly for slabs made of stone or similar, such as marbles, granites, but also ceramics and other building materials used for flooring and lining, which comprises means for grinding and/or polishing and/or shaping rims or edges and means for conveying workpieces to said grinding and/or polishing and/or shaping means.
Prior art grinding and/or polishing machines include a typically horizontal conveyor which consists of a roller track or of a belt whereon the slabs made of materials like stone, marble, granite, rock or the like are fed along grinding and/or polishing heads. Grinding and/or polishing heads consist of rotating grinding disks mounted on the shaft of a motor drive. Said heads are mounted on transverse guides and are moved back and forth transverse to the slab feed direction so that the latter can be processed all over their width. In these well-known machines an effective processing can be only obtained by providing a great number of grinding heads on the conveyor, aligned in the slab feed direction. Hence, the grinding and/or polishing machine has huge dimensions and, besides being bulky , it is also very expensive.
Another drawback, which requires special means for controlling the grinding heads consists in that the peripheral edges of the slabs being ground or polished can have even considerable irregularities. In this case, the grinding or polishing disks, which are pressed to a predetermined extent, can partially penetrate these peripheral recesses or missing parts of the slabs, with the risk of remaining trapped therein, thereby causing the machine to operate improperly. The controlling systems which have to be provided to this end are complicated, expensive and do not always ensure a proper operation.
Machines for shaping the peripheral edges of stone pieces, such as slabs, or the like, are known. These machines are also typically provided with processing heads which interact with a workpiece, means being provided for relative motion of the piece with respect to the head. Here also, the processing head cooperates with very small areas of the peripheral edges of the pieces, whereby, in case of considerable irregularities, means must be provided for adjusting the relative transverse position between the shaping head and the edge of the slab being processed, which involves problems substantially similar to those related to grinders-polishers.
The invention is based on the problem of providing a machine which, by simple and inexpensive means, as compared to prior art machines, allows to perform grinding, polishing and/or shaping operations on the peripheral edges of stone pieces, or the like, without involving the above drawbacks.
The invention achieves these purposes by providing a machine as described hereinbefore, particularly for grinding and/or polishing stone slabs or the like and/or for shaping the peripheral edges thereof, which comprises at least one grinding and/or polishing and/or shaping tool, consisting of a plurality of grinding and/or polishing and/or shaping members which are mounted on annular conveyors, having the form of a continuous band, chain or belt, or on the surface of a roller shell, which means are rotatably driven.
Advantageously, the grinding and/or polishing and/or shaping means have the active surface on the radially outer peripheral side of the belt, band or chain along its annular path or of the roller.
Preferably, the grinding and/or polishing and/or shaping means consist of small belts having diamond elements like those used for cutting stone blocks and/or for cutting the latter into slabs.
Thanks to these arrangements, the invention allows not only to provide less expensive and cumbersome machines, but also to effectively use diamond elements, so that this processing can be extended to any type of material and not only to stones in general but also to marbles, granites, as well as ceramics and other building materials used for flooring and lining.
According to an advantageous embodiment, the belts or bands for polishing and/or grinding the faces of the slabs or the like extend all over the width of the workpiece feed path, a maximum width for workpieces being provided.
However, the belt/s or bands for shaping the edges are oriented in the workpiece longitudinal feed direction and are placed at the sides of the feed path.
Depending on the processing operation being performed one single belt or band or several successive belts or bands cascaded in the workpiece feed direction may be provided.
In an advantageous embodiment, at least one grinding and/or polishing unit may be provided, comprising three parallel, adjacent and slightly spaced belts, which are driven together.
The belts of each unit may have identical or different grinding members as regards the grinding grain thereof, i.e. of the diamond powder or particles.
When the grain is different, the belts are disposed in such a manner that the members having a decreasing grain are placed after those with a larger grain with reference to the piece feed direction.
The belts or bands have at least one straight branch parallel to the conveying surface and at a distance therefrom so as to be able to interact with the surface to be processed of the pieces.
At least the above active branch of the belt/s interacts with belt-guiding means, whereas the contact surface between the belts and the guide means may be plane, semiplane, inclined, V-shaped, semicircular, etc.
In a construction embodiment, the belts or bands have, for instance, an inner continuous and axial appendix which is designed for engagement in guide throats of grooved belt-guiding means.
According to an embodiment, the belt-guiding means consist of a belt-guiding plate which has a groove for engaging the belt or the inner rib thereof and extends substantially all along the active branch, continuously or in sectors, whereas at the ends of the plate, return and drive pulleys are provided, which are preferably substantially placed outside the workpiece feed path.
The belt-guiding grooves are preferably associated to means for feeding a fluid into the grooves to generate a slide bearing, e.g. with a so-called "aquaplaning" effect.
In a variant embodiment, the belt-guiding means consist of lines of wheels or rollers having annular guide grooves, which are spaced in a predetermined manner along the active branch of the belt.
Combinations of guide grooves and rollers as described in the two above exemplary embodiments may be also provided.
The belts are arranged transversely to the translation motion of the workpieces, allowing to perform roughing, grinding and shaping operations, and are parallel to the surfaces to be processed.
In accordance with a further improvement, advantages my be obtained from providing, downstream with respect to the workpiece feed motion, belt thrust-bearing means contrasting the transverse thrust exerted against the belts by the workpiece being fed.
Advantageously, these thrust-bearing means consist of idler rollers or wheels arranged in a certain order along the active branch of the belt/s and supported so as to rotate about axes perpendicular to the active surface of the belts and in contact with the side edge of the associated belt, which is provided downstream with respect to the workpiece feed direction.
According to a further characteristic, in combination with or alternatively to the grinding and/or polishing belts or bands tools for shaping the peripheral edges of the slabs are provided, particularly parallel to the piece feed direction and also consisting of belts or bands having shaping members of the diamond type, identical or similar to the cutting belts.
In this case, the belts are disposed at the sides of the conveyor and have an operating straight branch which is parallel to the workpiece feed direction.
The belts are mounted on support guides to be driven in such a manner as to slide on an annular path with at least one operating straight path parallel to the workpiece feed direction.
The belts like the grinding ones may have diamond teeth shaped so as to complement the profile of the peripheral edge section of the piece to be obtained.
The bearing structure of the edge-shaping belts may be supported so that it can be inclined with respect to the piece conveying surface, whereby edges may be chamfered with various inclinations.
The edge-shaping belts may be also supported so that the distance of the active branch from the longitudinal median axis of the piece conveying path can be adjusted.
These belts my be also supported so as to enable level adjustment with respect to the workpiece conveying path.
For instance, when pieces, especially slabs having particularly irregular edges are being processed, the edge-shaping belts may be mounted so that hey can be progressively moved towards the central axis of the path, with the workpiece being stopped until the edge has been leveled and shaped.
Irregular side edges may be leveled by means of a special side leveling belt, specifically designed and supported for this task, whereas the shaping operation may be performed downstream from said leveling or edge-rectifying station, in a subsequent shaping station provided with a special shaping belt.
In combination with the shaping belt, means for trimming the irregular part of the side edges of the piece may be provided before the shaping belts and may consist of circular saws, of the band type or similar, or of cutting belts oriented perpendicular to the piece feed path and vertically movable against the workpieces.
The grinding and/or polishing and/or shaping belts or bands may be further mounted so that they can move towards or away from the surface to be processed of the pieces, and in combination with elastic members with a predetermined load of the active branches thereof against the surfaces being processed.
These load means may be also pressure-adjustable.
The polishing belts may be also supported so that they can be height-adjusted to set the operating position and possibly an idle position wherein they are at a distance from the surface to be processed with reference to the thickness of the workpieces.
When processing of edges on the sides transverse to the piece feed direction is also to be provided, further piece-turning means may be provided, which orient the other peripheral edges of the piece parallel to its feed direction.
In combination with the belts for polishing and/or shaping the peripheral edges of the workpieces, polishing tools may be provided.
These tools may consist of belts with polishing members, or of polishing rollers provided in such a position as to cooperate with the corresponding surfaces, like the belts.
The belts for shaping the edges and those for grinding, as well as the means for trimming the edges and the polishing means may be combined in a single machine, having a plurality of successive stations, in which said processing means are provided and along which stations the piece feed path develops.
Several machines may be also provided, each designed for a specific processing task, such as a machine for grinding and/or polishing piece faces; a machine for shaping and/or polishing edges, possibly combined with edge-trimming means or even with a specific edge-trimming machine.
By this arrangement, operations requiring longer processing times are prevented from engaging stations designed for performing other operations requiring slower processing times. Single machines are also thinner and smaller in construction and can be more easily placed in work environments with various volume characteristics.
Further improvements of the invention will form the subject of the dependent claims.
Fig. 1 is a diagrammatic plan view of an embodiment of a machine according to the invention which has an edge-shaping station, a grinding station and stations for polishing the edges and the ground face of the workpiece.
Fig. 2 is a sectional view of the machine as taken across line II-II of fig. 1.
Fig. 3 is a sectional view of the machine as taken across line III-III of fig. 1.
Fig. 4 is a cross-sectional view of the belt-guiding plate and of the small belts thereof in a unit comprising three adjacent belts preferably having diamond teeth with different diamond sizes.
Figs. 5 and 6 are cross-sectional views of the diamond toothed belts for two different profiles of the side edges of the workpiece.
Fig. 7 is a side view of a machine according to the invention, having several cascaded grinding and/or polishing stations.
Fig. 8 shows, by way of example, with reference to a single belt, the transverse thrust-bearing means associated to the belts.
Fig. 9 is a view as shown in fig. 3, of a variant embodiment of the invention, wherein instead of stationary guide grooves, the active branch of the belt is guided on a line of grooved rollers or wheels.
Fig. 10 is a diagrammatic cross sectional view of the guide plate which bears three parallel lines of grooved rollers as means for guiding the active branches of three adjacent belts.
Referring to fig. 1, a grinding and polishing machine, for instance for grinding/polishing slabs made of materials like marble, granite, or the like, includes a conveyor 1 which can be of any type, such as a rotatably driven continuous band, a bearing surface movable on guides by motor drives, an idler track combined with pushers, etc. In the example as shown in fig. 1, the conveyor 1 consists of a conveyor band whose conveying branch is oriented horizontally.
In an intermediate position in the conveyor band 1, a grinding station 20 is provided, consisting of at least one diamond toothed belt, preferably of a unit of three diamond toothed belts 2, 2', 2''. The belt/s 2, 2', 2'' are similar to the belt/s used in combination with arms for cutting stone or rock. The three belts are closed and returned about two pulleys 3, 4 which rotate about a horizontal axis oriented in the feed direction of the conveyor 1. The two return pulleys 3, 4 are disposed substantially out of the corresponding longitudinal, side edge of the conveyor 1, so that they form an active branch 102 which is parallel or substantially parallel to the conveying surface, while facing the latter. The belts 2, 2', 2'' are oriented by their peripheral upper edge towards the conveying surface and by their longitudinal axis transverse to the conveyor 1, particularly perpendicular thereto. A motor M drives rotatably at least one of the pulleys 4.
As also shown in figs. 2 and 4, the active or operating branches of belts 2, 2', 2'' are guided by common guide plates 5 oriented parallel thereto. Particularly, on the radially inner or rear side, the belts have, as is known in machines having a cutting arm, a central appendix which may be continuous or consisting of a plurality of extensions, spaced in the longitudinal direction of the belts. This appendix 202 is engaged inside a guide consisting of a groove 205 complementing the appendix 202 of the belts 2, 2', 2''. The guide has a plurality of holes 105, communicating with a distribution chamber 6, which can be common, as shown, or separated for each guide 105 of each belt. Thanks to this arrangement, the guide is constantly lubricated during operation by a plurality of water jets which form a sort of slide bearing, water also having the function to keep the guide free from cutting and grinding residues. The belt has a T cross section and the guide also has bearing and sliding surfaces for the wings of the T shape, in addition to those for the extension 202.
Obviously, the section shapes of the belt 2, 2', 2'' can vary though still contributing to produce the desired effect.
Belts as those in use in the machine according to the invention consist of a plurality of diamond teeth 302 which are typically equally spaced all along a metal wire or more twisted wires, whereas a body made of an elastic plastic material 402 similar to rubber coats the wire filling the spaces between the diamond teeth, substantially flush therewith and provides the belt with a continuous final shape. Such belts are known and described in greater detail, for instance in patent EP 773092.
Diamond toothed belts have diamond coated teeth with different grain sizes and are generally disposed in such an arrangement that the grain sizes decrease in the piece feed direction.
Typically, the active surface of the diamond teeth 402 is plane and oriented parallel to the face of the piece to be ground.
Also, the conveyor 1 and the grinding belts 2, 2', 2'' are supported in such a way as to enable distance adjustment. This may be provided either by a lifting and lowering movement of the conveyor with respect to the belts, or by a lifting and lowering movement of the belt, or even thanks to vertical adjustment means either of the conveyor 1 or of the belts 2, 2', 2''.
In the illustrated embodiment, the active branches 102 of the belts 2, 2', 2'' are guided in the belt guiding plate which is stationary. Alternatively, operating pressers may be provided, which act on the plate, e.g. linear actuators and/or elastic pressers, such as springs or the like. These pressers may be gauged so as to ensure a predetermined constant pressing force exerted by the active branches of the belts on the workpiece.
No specific embodiment of the vertical adjustment means of the conveyor 1 and/or of the belts 2, 2', 2'' and of the possible pressers is shown in detail herein, because these embodiments are not complex in construction and may be provided in any way, even with known elements.
Downstream from the grinding station, a polishing station 21 is provided. With reference to fig. 1, it has a polishing roller 8, which can rotate about a horizontal axis, parallel to the conveying surface and substantially transverse to the feed direction A of the piece P on the conveyor 1.
The polishing roller 8 may be rotatably driven by a special motor 7 and is supported at its ends, which are out of the longitudinal side edges of the conveyor 1. As described with reference to the belts 2, 2', 2'', the polishing roller 8 may be supported in such a way as to enable height adjustment and/or have pressers to exert a predetermined operating pressure of the polishing roller 8 on the workpiece P.
With reference to the above description, particularly when height adjustment means for the grinding belts 2, 2', 2'' and for the polishing roller 8 are provided, the machine according to the invention has an additional functionality with respect to prior art grinding machines. By providing height adjustment means for said two parts with respect to the conveyor surface at the ends of the polishing roller 8 and at the return pulleys of the belts 2, 2', 2'', grinding and polishing operations may be performed even on pieces with inclined exposed surfaces, i.e. wedge- or trapezoid-shaped pieces. In this case, the two return pulleys of the belts 2, 2', 2'' and the ends of the polishing roller may be positioned at different heights, thereby providing that the active branches of the belts 2, 2', 2'' and the tangent line between the polishing roller and the workpiece are accordingly inclined with respect to the horizontal plane. This functionality is not limited to grinding, but may be also used to thin the workpiece as desired .
With reference to the polishing station 21, polishing means may be provided, alternatively consisting of polishing belts having polishing members equally spaced over the belt, or even in a continuous arrangement thereon, instead of the diamond teeth. This variant is shown in fig. 7, in which the three belt unit is denoted with numeral 8'.
Obviously, as shown in the variant of fig. 7, the machine according to the invention can also have more than one grinding station 20 and/or polishing station. The grinding stations 20 can have each one belt 2 or more belts 2, 2', 2'' grouped therein.
Still referring to figs. 1 to 3, the machine according to the invention can have, alternatively to or in combination with the station/s for grinding 20 and polishing 21 the face of the workpiece P one or more stations for shaping 22 and polishing 23 the peripheral edges of the piece P, e.g. of a slab or the like.
In this case, the conveyor 1 is narrower than the worpiece, whereas on at least one longitudinal side of the conveyor 1 a diamond toothed belt 10 is provided, which faces, by its active branch, the facing edge of the workpiece P and is parallel to the feed direction A of the conveyor 1.
Advantageously, by providing two shaping belts 10, each on one of the opposite longitudinal sides of the conveyor, the opposite peripheral edges of the workpiece can be shaped.
Each diamond toothed belt 10 for shaping the edges is returned about two pulleys 11 whose axis is oriented perpendicular to the surface which conveys the piece P and at least one of which is rotatably driven by a motor 111. As described for grinding belts 2, 2', 2'', the active branch 110 of the shaping belt may run inside a guide also provided with holes 105 for feeding a washing and lubricating liquid, particularly water. The guide 5 also has a continuous throat 205, wherein an extension 210, which may be continuous or composed of individual equally spaced projections on the inner face of the belt 10, is slidably engaged.
The grinding belt 10 may be supported in such a way as to enable height adjustment with respect to the conveyor surface 1, by moving the surface or by moving the belt or by a combination of the two adjustments, as provided for the grinding belts 2, 2', 2''. Also, still like the grinding belts 2, 2', 2'', the shaping belt 10 may be provided in combination with either operating and rigid or elastic pressers, whereby the active branch of the belt is pushed with a predetermined force against the edge of the piece P.
According to a further possible characteristic, the two return pulleys 11 are supported so that they can be inclined together with respect to the perpendicular orientation of their axes, in such a manner that their diamond teeth 310 are inclined with respect to the surface of the peripheral edge facing them, in order to perform chamfers or the like.
The active side of the diamond teeth 310 may be rectilinear or shaped in various ways, concave, rounded and symmetrical with respect to the median horizontal plane of the workpiece, asymmetrical or with particular curve shapes.
The inclination of the shaping belt 10 with respect to the horizontal plane may be adjusted to a stable position, or the oscillation may be continuous so as to obtain a rounded shape with the help of flat teeth only.
In case of an inclined stable positioning, the teeth 310 may have the suitable shaping to provide the peripheral edge of the workpiece with the desired shape.
Figs. 5 and 6 show two examples of shaping belts 10 having round concave or V-shaped teeth 310 respectively. The construction of the shaping belt 10 is very similar to that of the above described grinding belts 2, 2', 2'' and hence similar to the diamond toothed belts used for cutting.
Obviously, the examples of figs. 5 and 6 are not intended to be exhaustive, no constraint being provided for the shape of the diamond teeth.
When the peripheral edges of the workpiece are not rectified, means for rectifying or trimming said edges may be provided.
Particularly, in case of slight irregularities, they can be rectified or removed by using the shaping belts, which, in this case, can be further moved to a predetermined extent against the edge to be processed, e.g. by mounting the return pulleys 11 on special horizontal transverse slides or anyway parallel to the surface of the conveyor 1. The supporting slides and the means for driving them are not shown because they are not a problem for the skilled person and may be made in any manner.
In case of considerable irregularities, trimming belts or similar may be provided in a station before the edge shaping station. The trimming means may be of any type, even possibly cutting belts mounted in the piece feed direction and vertically movable against it, as well as adjustable in their transverse position, i.e. an their distance from the central axis of the conveyor.
When the piece is not rectangular, or when edges transverse to the rectangular piece feed direction are to be processed, a piece-turning member may be provided, for instance after the edge-shaping station, whereby the piece is oriented to enable processing of a further edge, which before was oriented transverse to the piece feed direction.
Said operating units, i.e. the piece-turning member and the edge-trimming means may be provided in combination with the shaping belts 10 integrated in the same machine or in a separate machine. Similarly, the shaping belts and said units for trimming and rotating the piece can be integrated in a grinding or polishing machine.
The edge-shaping station 22 is followed by an edge-polishing station 23, which can include one or more polishing rollers 13 having perpendicular axes, arranged along the longitudinal edges of the conveyor 1 and possibly allowing orientation and/or adjustment as regards the distance from the corresponding longitudinal edge of the conveyor.
Alternatively, as shown in figure 7, the rollers may also consist of one or more polishing belts 13', as already described with reference to the means for polishing the workpiece faces.
A piece-turning member may be also associated to the edge-polishing station 23, downstream or upstream therefrom, in order to bring different peripheral edges into the operating position, with different orientations.
A considerable advantage in using diamond toothed belts for grinding exposed faces of slabs or the like and for shaping edges consists in that, due to their remarkable construction simplicity and functional effectiveness, these inventive arrangement can be used both in very simple and small-sized machines specially designed for grinding and/or polishing and for edge-shaping and/or polishing and, by a combined assembly, in integrated machines, which can perform all the above operations, possibly automatically, like in timber industry. All this, here too, without requiring an excessively huge structure and an excessively complex machine.
Diamond belts, due to the heavy tasks they currently have in cutting marble blocks in quarries are highly resistant and strong tools, which provide the machine of the invention with operational safety features and require little maintenance.
With reference to the above disclosure, diamond toothed rollers, for instance, may be provided instead of diamond toothed belts. This arrangement might provide rollers having one or more lines of diamond teeth arranged radially and solidarized by an injection of plastic. Here, face grinding could be performed by providing the rollers arranged transversely to the piece feed direction and above the piece with diamond teeth rings, in circumferential intercalation and partially axially superposed so as to prevent them from being spaced in the axial direction. This construction is a solution to the above problems of prior art. However, the rollers could be more difficult to manufacture with the necessary tolerances, and especially more expensive than belts, even because belts are fabricated with processes that have been used for a long time and do not require special manufacturing facilities.
Fig. 8 shows an advantageous variant embodiment of the belt-guiding plate 5 for diamond belts 2. Here, for simplicity reasons, this improvement is shown with reference to one belt, but may be also applied easily and with appropriate adjustments, to the belt-guiding plate of fig. 4 whereto more parallel and adjacent belts are associated.
The arrangement of fig. 8 consists in that, in order to counterbalance the transverse forces acting on the belt 2 and produced by the workpiece feed transverse, particularly perpendicular thereto, thrust-bearing guides or means 30 are provided on the downstream side of each belt. These thrust-bearing guides or means may be made in any manner and may consist of a stationary slide guide along which the corresponding side of the belt, preferably the one without diamond teeth and inserts runs, adhering against it, while it is possible or advantageous to provide in this case lubricating fluid bearing means like those provided in the guide of the associated belt.
Alternatively, the thrust-bearing means may consist of means whose contact surfaces with the sides of the belt slide together with the associated contact surface of the belt 2, such as a line of rollers or a belt or a band. In this case, the rollers and/or the belt or the band may be idle and be dragged by the grinding belt 2, or even driven by special drives. Fig. 8 shows, by way of schematic example, the variant of the thrust-bearing idlers denoted with numeral 30.
With reference to figs. 9 and 10, the latter show a variant embodiment of the belt-guiding means. In this case, instead of the stationary guiding grooves with fluid fed to generate slide bearings with a so-called aquaplaning effect, the belt/s are guided by a line of rollers 31 with peripheral coaxial annular grooves 131. The rollers may be at any distance from each other, possibly even different from each other. The rollers may be regularly supported to be in line in the grinding surface, even by elastic and shock-absorbing suspensions.
Fig. 10 shows a construction example of guide means for rollers 31, like in fig. 4. Here, a bracket 33 bears a line of horizontal and parallel adjacent axles for rotatable support of the guide rollers 31.
Each axle can bear, in line with the guide rollers 31 of the corresponding belt 2, a roller for one of more adjacent belts 2 respectively. In this case, three belts are provided. The rollers 31 are coaxial to each other and can be separated or made from one piece in a single guide roller having several peripheral coaxial annular grooves, as schematically indicated by the dashed lines 32 connecting the peripheral shells of the individual rollers 31 in fig. 10.
In this variant embodiment, means for feeding fluid may be also provided, said fluid having almost exclusively the function to wash the rotary roller supports. Moreover, also in this exemplary embodiment, thrust-bearing means may be provided for each belt, which may be made in any manner, as described in the previous paragraphs, relating to fig. 8.
Obviously, the invention is not limited to what is described above and claimed below but may be greatly varied especially as regards construction. Thus, for instance, with reference to the embodiments as shown in figs. 4 or 10, the individual parallel belts and/or the successive units of grinding belts may be provided at different levels, for workpiece roughing or thickness calibration purposes, i.e. at progressively reducing levels with respect to the supporting surface of the workpiece in the workpiece feed direction. All this without departure from the guiding principle disclosed above and claimed below.

Claims

1. A machine for stone surface treatment, particularly for slabs made of stone or similar, which comprises means (2, 2', 2'', 10, 8, 8', 13, 13') for grinding and/or polishing and/or shaping rims or edges and means (1) for conveying workpieces (P) to said grinding and/or polishing and/or shaping means (2, 2', 2'', 10, 8, 8', 13, 13'), characterized in that it comprises at least one grinding and/or polishing and/or shaping tool, consisting of a plurality of grinding and/or polishing and/or shaping members (402, 310) which are mounted on annular conveyors, having the form of a continuous band, chain or belt or on the peripheral shell of a roller or the like, which means are rotatably driven (2, 2', 2'', 10, 8', 13').

2. A machine as claimed in claim 1, characterized in that the grinding and/or polishing and/or shaping means (310, 402) have the active surface on the radially outer peripheral side of the belt, band or chain on its annular path (2, 2', 2'', 10).

3. A machine as claimed in claim 1 or 2, characterized in that the grinding and/or polishing and/or shaping means (310, 402) consist of small belts having diamond elements like those used for cutting stone blocks and/or for cutting the latter into slabs.

4. A machine as claimed in one or more of the preceding claims characterized in that the belt/s or bands (2, 2', 2'', 10) for polishing and/or grinding the faces of the slabs or the like extend all over the width of the workpiece feed path, a maximum width for workpieces (P) being provided.

5. A machine as claimed in one or more of the preceding claims characterized in that the belt/s or bands (10) for shaping the edges are oriented in the workpiece (P) longitudinal feed direction and are placed at the sides of the feed path (1).

6. A machine as claimed in one or more of the preceding claims characterized in that it comprises one single belt (2, 10) or band or several successive belts or bands (2, 2', 2'', 10) cascaded in the workpiece (P) feed direction (A).

7. A machine as claimed in one or more of the preceding claims characterized in that it comprises at least one grinding and/or polishing unit including two, three or more parallel belts, which are adjacent and slightly spaced, and which belts (2, 2', 2'') are driven together.

8. A machine as claimed in one or more of the preceding claims characterized in that the belts (2, 2', 2'') of each unit may have identical or different grinding members (402) as regards the grinding grain thereof, i.e. of the diamond powder or particles.

9. A machine as claimed in one or more of the preceding claims characterized in that the belts (2, 2', 2'') with different grains are disposed in such a manner that the members (402) having a decreasing grain are placed after those with a larger grain with reference to the piece (P) feed direction (A).

10. A machine as claimed in one or more of the preceding claims characterized in that the belts or bands (2, 2', 2'', 10, 8', 13') have at least one straight branch (102, 110) parallel to the conveying surface (1) which is provided at a distance therefrom so that they can interact with the surface to be processed of the pieces (P).

11. A machine as claimed in one or more of the preceding claims characterized in that the several successive belts (2, 2', 2'') are at a distance from the workpiece (P) conveying surface, which progressively decreases for each successive belt after the other with reference to the workpiece (P) feed direction.

12. A machine as claimed in one or more of the preceding claims characterized in that the belts or bands (2, 2', 2'', 10) have a rear continuous and axial appendix (202, 210) which is designed for engagement in grooved guide means (5, 205; 31, 131) and in the return or drive pulleys (3, 4, 11) arranged at the ends of said guide means (5, 205; 31, 131), preferably substantially out of the piece (P) feed path (1).

13. A machine as claimed in claim 12, characterized in that the means for guiding the belt/s (2) consist of guide throats (5, 205) of a belt-guiding plate (5), in combination with fluid fed to generate a low-friction slide bearing, particularly with a so-called aquaplaning effect.

14. A machine as claimed in one or more of the preceding claims characterized in that the means (31, 131) for guiding the belt/s (2, 2', 2'', 10) consist of lines of rollers (31) with coaxial annular throats (131), which are rotatably supported, idle or motor-driven, and which rollers (31), in case of several adjacent belts (2, 2', 2'') are separated or integrated in a single roller (32), having several coaxial annular grooves.

13. A machine as claimed in one or more of the preceding claims characterized in that each grinding belt (2, 2', 2'') which acts on a workpiece (P) having a feed direction which is transverse, particularly perpendicular to the active branch of the belts (2, 2', 2'') is provided with transverse thrust-bearing means (30) which are in contact with the side of their respective belts (2, 2', 2''), downstream therefrom with reference to the workpiece (P) feed direction.

14. A machine as claimed in claim 13, characterized in that the thrust-bearing means (30) consist of stationary guides along which the belt sides (2, 2', 2'') run, possibly in combination with fluid fed to generate a low-friction slide bearing, thanks to the aquaplaning effect.

15. A machine as claimed in claim 13, characterized in that the thrust-bearing means have contact surfaces with the belt sides (2, 2', 2''), moving therewith or rolling thereon, such as thrust-bearing belts or bands or roller lines (30), which may be idle and dragged by their respective belt (2, 2', 2'') or even motor-driven.

16. A machine as claimed in one or more of the preceding claims characterized in that, in combination with or alternatively to the grinding and/or polishing belts or bands (2, 2', 2'', 8), tools (10) for shaping the peripheral edges of the pieces (P) are provided, particularly parallel to the piece (P) feed direction (A) and also consisting of belts or bands having shaping members of the diamond type (301), identical or similar to diamond toothed cutting belts.

17. A machine as claimed in one or more of the preceding claims characterized in that the peripheral edge shaping belts (10) are disposed at the sides of the conveyor (1) and have an operating straight branch (110) which is parallel to the workpiece (P) feed direction (A).

18. A machine as claimed in one or more of the preceding claims characterized in that the belts (10) are mounted on support guiding means (5; 31) to be driven in such a manner as to slide on an annular path with at least one operating straight path (110) parallel to the workpiece (P) feed direction (A).

19. A machine as claimed in one or more of the preceding claims characterized in that the shaping belts (10) are like the grinding ones (2, 2', 2'') and may have diamond teeth (310) shaped so as to complement the profile of the peripheral edge section of the piece (P) to be obtained.

20. A machine as claimed in one or more of the preceding claims characterized in that the bearing structure of the edge-shaping belts (10) can be inclined with respect to the piece (P) conveying surface (1), whereby edges may be chamfered with various inclinations.

21. A machine as claimed in one or more of the preceding claims characterized in that the angular inclination movement of the peripheral edge shaping belts (10) may be steadily preset or be a continuous reciprocating oscillation movement.

22. A machine as claimed in one or more of the preceding claims characterized in that the edge-shaping belts (10) are supported so that the distance of the active branch (110) from the longitudinal median axis of the piece (P) conveying path (1) can be adjusted.

23. A machine as claimed in one or more of the preceding claims characterized in that the edge-shaping belts (10) are supported so that their level with respect to the piece (P) conveying path (1) can be adjusted.

24. A machine as claimed in one or more of the preceding claims characterized in that the belts (10) for shaping the peripheral edges of the pieces (P) are supported in such a way as to be progressively movable towards the central axis of the path (1) run by the piece (P) and away therefrom to perform rectifying and leveling operations on the peripheral edge, while shaping it.

25. A machine as claimed in one or more of the preceding claims characterized in that, in combination with the peripheral edge shaping belt/s (10), said belts are provided downstream from means for leveling or trimming said peripheral edges, which may consist of belts for leveling or rectifying said edges and/or of trimming tools operating in the piece (P) feed direction (A).

26. A machine as claimed in one or more of the preceding claims characterized in that the grinding and/or polishing belts (2, 2', 2'', 8')) are supported so that their distance from the workpiece (P) conveying surface (1) can be adjusted.

27. A machine as claimed in one or more of the preceding claims characterized in that the belts for grinding and/or polishing the face of the piece (P) and those for shaping and/or polishing (10, 13') the edges of said piece (P) can be loaded to a predetermined extent, by means of rigid or elastic pressers, with the active branches (102, 210) thereof against the surfaces being processed.

28. A machine as claimed in one or more of the preceding claims characterized in that it provides, in combination with at least the edge-shaping belts (10) and/or with the polishing means associated thereto, piece-turning means which orient the other peripheral edges of the piece parallel to its feed direction.

29. A machine as claimed in one or more of the preceding claims characterized in that, in combination with the belt/s (2, 2', 2'') for grinding the exposed face of the piece (P) and/or with the belts (10) for shaping the peripheral edges thereof, polishing tools (8, 13, 8', 13') are provided, downstream from their respective belts (2, 2', 2'', 10).

30. A machine as claimed in one or more of the preceding claims characterized in that the polishing means consist of one or more belts (8', 13') having polishing members, or of polishing rollers (8, 13), placed in such a position as to cooperate with the corresponding surfaces, ground or shaped by the grinding and/or edge shaping belts (2, 2', 2'', 10).

31. A machine as claimed in one or more of the preceding claims characterized in that the belts (2, 2', 22) for grinding the face/s of the piece (P) and the polishing means (8, 8') are mounted with their ends out of the side edges of the piece (P) conveyor (1), and supported in such a way as to be movable to different levels, so as to generate an inclination of the active branches (102) or of the tangents with the piece (P) with respect to the conveying surface.

32. A machine as claimed in one or more of the preceding claims characterized in that the means for grinding the faces of the pieces (P) and the means for shaping the peripheral edges of the pieces (P) consist of rollers, provided, at their periphery, with diamond teeth arranged on the peripheral shells of rollers, to perform a homogeneous grinding and/or shaping operation.

33. A machine as claimed in claim 32, characterized in that the radial teeth are spaced and arranged on at least one or more annular strips of the rollers and that each annular strip of radial diamond teeth has staggered teeth with respect to the adjacent strip of teeth, the teeth of the two strips being partly axially superposed.

34. A machine as claimed in one or more of the preceding claims characterized in that it has one or more cascaded stations (20) for grinding the face of a workpiece (P).

35. A machine as claimed in claim 34, characterized in that it has one or more means for polishing a face of the workpiece (P).

36. A machine as claimed in one or more of the preceding claims characterized in that it has at least one station (22) for shaping the peripheral edges of the workpiece (P).

37. A machine as claimed in claim 36, characterized in that it has at least one station (13, 13') for polishing the shaped peripheral edges of workpieces (P).

38. A machine as claimed in one or more of the preceding claims characterized in that it has a combination of one or more stations (20, 21, 22, 23) for grinding a face of the piece, for polishing it, for shaping the peripheral edges of the piece and for polishing them, integrated therein.

39. A machine for stone surface treatment, particularly for slabs made of stone or similar, wholly or partly as described, illustrated and for the purposes stated herein.