MACHINE TOOL FOR SURFACE PROCESSING OF PRODUCTS OF STONE MATERIAL OR THE LIKE

Field of the invention

The present invention is generally applicable to the processing of stones and the like and particularly relates to a machine tool for surface processing of slabs or products having a flat surface of stone material or the like.

Such machine may be particularly used for surface grooving or scratching of products of hard materials, such as marble, granite, stoneware, porcelain, stones, stone material, cementitious material, as well as synthetic or metal materials and the like.

State of the art

Surface processing of products made of cement, stone or even metal materials, to impart a particular functional feature or aesthetic effect thereto is known to be carried out by special cutting tools, such as grooving tools, scratching rolls, or the like.

Typically, these tools are fixedly or removably fitted to support structures, whose configuration depends on the size of the tools and of the products to be processed.

The motion of these tools is achieved by common motor means, allowing several working parameters, such as depth of cut, rotation speed, cutting angle, to be controlled manually or by computer numerical control.

The workpiece is then translated in a direction or a plane, to allow processing to be carried out all over its surface. Otherwise, the toolholder arm may be slid along the plane defined by the processing surface.

Nevertheless, these prior art solutions only afford very little tool motion control, which is generally limited to interpolated control of three axes having a fixed center of rotation.

As a result, a very limited range of patterns may be formed on the working surface.

Therefore, if several faces or portions of the workpiece have to be machined, inconvenient and difficult displacement operations have to be carried out.

In an attempt to obviate one or more of the above drawbacks, a number of solutions have been proposed, allowing adjustment of tool position relative to the workpiece, in several different numbers of degrees of freedom.

EP-B1 -0769349 discloses a machine for scratching hard plates, e.g. made of stone or marble, in which the position of an abrasive roll may be adjusted relative to the workpiece. To this end, the roll is supported by a structure which allows to change the angle of its axis of rotation with respect to the plate feed direction, and to move the roll in a vertical plane. While this solution allows the roll to be moved in three orthogonal directions, it does not allow independent control of motions along each of such directions. As a result, the range of processing patterns that can be formed by this machine is also limited in that the working surface cannot be machined simultaneously in different areas, at different depths and/or different cutting angles.

Therefore, if different effects are desired on different areas of the workpiece surface, the cutting parameters have to be reset, which considerably increases processing times and reduces the throughput of the whole apparatus .

Summary of the invention

The object of this invention is to overcome the above drawbacks, by providing a machine tool for surface processing of products of stone material or the like that is highly efficient and relatively cost-effective.

A particular object is to provide a surface processing machine which allows to independently control the motion of cutting tools along three separate directions in space, thereby allowing acquisition of a greater number of degrees of freedom in the positioning thereof.

A further object is to provide a machine tool that allows to increase the combinations of tool motions in space, thereby providing a wider range of patterns on the working surface.

Another object of this invention is to provide a machine that allows the various cutting tools to interact with the working surface with different cutting parameters from one area to another, thereby further increasing the variety of surface patterns that can be formed on the workpiece.

A further object of this invention is to provide a machine that allows slab processing to be performed either by moving the slab with the machine being stationary and by moving the machine while the slab is held stationary, which further allows surface processing to be performed on any plane of the product.

Yet another object of the invention is to provide a machine for surface processing of slabs whose motions may be coordinated and interpolated, even during operation, through processing type-specific computer programs, thereby increasing throughput.

These and other objects, as better explained hereafter, are fulfilled by a machine tool for surface processing of products of stone material or the like, in accordance with claim 1 , which comprises a support structure which is fitted with at least one toolholder element, whose axis of rotation is substantially parallel to the working

surface and which is adapted to hold one or more cutting tools, first drive means for rotating the toolholder element about an axis of rotation and means for imparting controlled motion to the toolholder element relative to the working surface.

The invention is characterized in that the controlled motion means comprise guide means for imparting independent translational motions to the toolholder element, along first and second directions substantially parallel to the lying plane of the slab and a third direction substantially perpendicular to the other two directions.

The invention is further characterized in that the controlled motion means comprise second drive means for imparting rotational motions to the toolholder element, about an axis of revolution substantially parallel to the third motion direction.

Thanks to this arrangement, the tool holder element will have a great number of degrees of freedom during motion, thereby increasing its combinations of motions in space.

Thus, the machine can form a wide range of patterns on the working surface.

Advantageously, the guide means may comprise a first slide which is anchored to the support structure and is substantially parallel to the first motion direction.

Furthermore, the second drive means may comprise a stationary plate which is mounted over the first slide and has a rotating plate fitted thereon which is substantially parallel to the former and is susceptible of rotating about the axis of revolution.

Also, the guide means may comprise a second slide substantially parallel to the second direction, which may be further mounted over the rotating plate.

Thanks to this additional feature of the invention, the toolholder element may be moved along two different directions, parallel to the lying plate of the slab, the angle formed thereby being susceptible of changes even during operation, thereby increasing the number of toolholder position combinations.

The guide means may preferably comprise at least one pair of third slides substantially parallel to the third direction, on which the end supports of the toolholder element are anchored, to allow independent translational motion thereof.

Thanks to this additional feature, the machine of the invention allows the various cutting tools to interact with the working surface with different cutting parameters from tool to tool, thereby further increasing the variety of surface patterns that can be formed on the workpiece.

Advantageously, the support structure may be anchored to a stationary base having a movable surface for conveying the slabs to be processed in a predetermined feed direction.

Alternatively, or in addition, the support structure may be mounted on conveyor means, which can impart a translational motion to the machine relative to a stationary base having a fixed support surface for the slabs to be processed.

Thus, the slab may be processed by moving the slab with the machine being stationary, or by moving the machine while the slab is held stationary on the fixed support surface of the base, or by moving both the slab and the machine.

Preferably, the support structure can be positioned either above or below the lying plane, to process either the top surface or the bottom surface respectively of each slab.

Thanks to this feature, the invention allows processing to be performed on any plane of the product.

Also, the machine may be controlled by a computer control unit, which is operatively connected to first, second, third and fourth actuator means, and is in turn controlled by a program for controlling the position and speed of the first, second and third slides and the rotating plate associated to specific processor means.

Thanks to this particular configuration, the machine of the invention allows to coordinate and interpolate all the motions of the toolholder element, thereby allowing the use of processing-specific programs.

Furthermore, the cutting parameters of each tool may be changed without stopping the processing operations, thereby accordingly increasing the machine's throughput.

Brief description of the drawings

Further features and advantages of the invention will be more apparent from the detailed description of a preferred, non-exclusive embodiment of a machine for surface processing of slabs of stone material or the like according to the invention, which is described as a non-limiting example with the help of the annexed drawings, in which: FIG. 1 is a perspective view a system for surface processing of slabs, which includes a machine according to the invention;

FIG. 2 is a perspective view of a machine according to the invention; FIG. 3 is a top view of the machine of FIG. 2; FIG. 4 is a side view of the machine of FIG. 2.

Detailed description of a preferred embodiment

Referring to the above figures, the machine of the invention, generally designated by numeral 1 , may be used to form surface patterns on slabs or products having a flat surface and made of a stone material, such as rock, marble, granite, stoneware, and stone materials in general, or of synthetic or metal materials, or the like.

According to the invention, the machine 1 may be part of a processing line I, for scratching, grooving or the like, on the surface S of a workpiece, such as a slab L, which is fed along the line I on a movable conveying surface N, e.g. a belt conveyor or a series of powered rollers, in a substantially horizontal feed direction A.

The slab L is placed on a support surface P which defines a lying plane π for its working surface S.

As shown in FIG. 2, the machine 1 comprises a support structure 2, which is fitted with a substantially cylindrical toolholder element 3, the latter being susceptible of rotating and be driven into rotation about its axis Ri substantially parallel to the working surface S, at an angular speed D ₁ , by first drive means 4.

The toolholder element 3 supports a plurality of cutting tools 6 on its outer surface 5, which are adapted to carry out the required processing.

Means are also provided for imparting controlled motion 7 to the toolholder element 3 relative to the working surface S.

A peculiar feature of the invention is that the controlled motion means 7 comprise guide means 8 for imparting independent translational motions to the toolholder element 3, along first and second directions X, Y, substantially parallel to the lying plane π and a third direction W substantially perpendicular to the other two directions.

The toolholder element 3 is further supported to be rotatable about an axis of revolution R ₂ substantially parallel to the third direction W, and may be driven into rotation about such axis by appropriate drive means 9, at an angular speed D ₂ .

This arrangement provides a great number of combinations of motions and adjustments of the toolholder element 3 along each of the directions X, Y, W, during positioning thereof relative to the working surface S, which allows to change the geometry of markings and the pattern that can be formed thereon.

The support structure 2 may be anchored, by means of a fastening base 10 to a stationary base B which is connected to the movable conveying surface N of the slabs L to be processed.

The guide means 8 may comprise a first slide 11 which is anchored to the support structure 2 and is substantially parallel to the first motion direction X.

Furthermore, the second drive means may comprise a stationary plate 12 which is mounted over the first slide 1 1 and has a rotating plate 13 fitted thereon which is substantially parallel to the former and is susceptible of rotating about the axis of revolution R ₂ .

Also, the guide means 8 comprise a second slide 14 substantially parallel to the second direction Y, which may be further mounted over the rotating plate 13.

Therefore, the first and second slides 1 1 , 14 may be oriented within their own plane π' by staggering their respective motion directions X, Y by an angle α of 0° to 360°, without having to stop processing.

Conveniently, the guide means 8 may comprise a pair of third slides 15, 16 substantially parallel to the third direction W, and movable along respective axes W-I, W ₂ which are parallel and spaced along the direction r defined by the axis of rotation Ri of the toolholder element.

End supports 17, 18 of the toolholder element 3 may be anchored to each of the third slides 15, 16, to allow independent translational motions thereof w', w" along the axes W-i, W ₂ respectively.

According to a preferred non limiting embodiment of the invention, the axes W ₁ , W ₂ define a working plane π" for the toolholder element 3 which is substantially orthogonal to the lying plane π of the working surface S and is susceptible of rotating about the axis of revolution R ₂ .

Therefore, thanks to the possibility of imparting translational motions to the end supports 17, 18, hence the respective edge portions 19, 20 of the toolholder element 3, the latter may be oriented within the plane π" so that its axis of rotation Ri is not necessarily parallel to the lying plane π of the slab L.

Thus, the tools 6 on the outer surface 5 of the toolholder element 3 may interact with the working surface S, each with different cutting parameters, such as depth of cut or cutting surface.

This will further increase the range of patterns that can be formed on the surface of the slab L, thereby improving the processing quality.

As shown in FIG. 2, the tools 6 will be arranged in directions d substantially parallel to the axis of rotation R ₁ of the toolholder element 3 and in circumferentially equally spaced positions.

However, the tools 6 may be located on the outer surface 5 of the toolholder element 3 in any arrangement, even an uneven arrangement, without affecting processing results.

Also the tools 6 may be formed of one piece with the toolholder element 3, or removably mounted thereon to allow removal and possible replacement thereof

with other cutting tools either similar thereto or adapted to different processing operations.

This will avoid the need of replacing the whole toolholder element 3, the same machine 1 being usable for different processing operations.

Both the toolholder element 3 and the tools 6 may be formed from a material that is able to carry out the desired processing operations and to withstand the stresses derived from contact with the working surface S.

For instance, they may be formed from any metal alloy or similar material.

In accordance with the embodiment of the Figures, each slide 1 1 , 14, 15, 16 may be of the oil hydraulic type, having two cylinders 21 sliding parallel to the respective motion directions X, Y, W ₁ , W ₂ .

The first and second slides 1 1 , 14 may be fixed to the stationary plate 12 and the rotating plate 13 respectively by respective cylindrical sleeves 22, each allowing respective moving cylinders 21 to slide therein, which sleeves are fastened by respective anchor plates 23 to the rotating plate 13 or the stationary plate 12 by means of common fastening means, such as by welding.

The third slides 15, 16 may be connected to the second slide 14 by means of a metal frame 24, which is anchored to the ends of the latter.

Each slide 1 1 , 14, 15, 16 may be moved by first, second and third actuator means 25, 26, 27 respectively, which impart independent and bidirectional translational motions w, y, w, w', w" to the toolholder element 3 and its end supports 17, 18 along their motion directions X, Y, W, W-i, W ₂ .

Particularly, a pair of third actuator means 27, 27' is provided, which operate independently from each other to separately and independently orient the edge portions 19, 20 of the toolholder element 3 within the plane π".

Fourth actuator means 28 may be further provided which operate on the rotating plate 13 to promote controlled rotation D ₂ of the toolholder element 3 in both directions of rotation, about the axis of revolution R ₂ .

Preferably, the actuator means 25, 26, 27, 27', 28 may consist of motors, which may be of different types, possibly equipped with speed-reducing gears. For example, brushless motors may be used, with continuous control of speed and torque control.

For all the motions of the machine 1 , speeds and frequencies may be adjusted by special programs or individual manual settings and appropriate position sensors are preferably provided.

To this end, there may be provided a computer control unit, not shown due to its being known in the art, which is operatively connected to the actuator means 25, 26, 27, 27', 28 and may be, for example, an electronic control unit for providing control and interpolation of displacements along the motion directions X, Y, W, W ₁ , W ₂ .

The control unit is managed by processor means associated to a program for controlling the position and speed of the slides 1 1 , 14, 15, 16 and the rotating plate 13.

The control program may be an operator-configured or preinstalled software program, allowing automatic or semiautomatic operation of the machine 1.

While FIG. 1 shows a machine 1 above the working surface S, the machine may be also placed below or at any angle with respect to the horizontal plane π.

Finally, in an alternative embodiment, not shown, the machine 1 may be mounted, by the fastening base 10 of its support structure 2, to external translating means, which allow it to be displaced relative to a stationary base having a fixed support surface for the slabs to be processed.

Such translational motion will occur along a plane substantially parallel to the lying plane π, for instance along at least one of the first and second motion directions X, Y.

Both the movable conveying surface N, in the configuration of FIG. 1 and the stationary base in the alternative embodiment, may be arranged so that the lying plane π for the worksurface S is not necessarily horizontal.

The above description clearly shows that the invention fulfils the intended objects, and particularly the object of providing a machine for total control surface processing of slabs of stone materials or the like, which allows controlled and independent motion of the toolholder element 3 in at least three directions X, Y, W.

Furthermore, thanks to the provision of a pair of separately and independently controlled vertical slides 15, 16, different processing parameters may be used for the various tools, thereby providing a very wide range of surface patterns.

The machine of the invention is susceptible of a number of changes and variants, within the inventive concept disclosed in the appended claims. All the details thereof may be replaced by other technically equivalent parts, and the materials may vary depending on different needs, without departure from the scope of the invention.

While the machine has been described with particular reference to the accompanying figures, the numerals referred to in the disclosure and claims are only used for the sake of a better intelligibility of the invention and shall not be intended to limit the claimed scope in any manner.