EP3493962B1

EP3493962B1 - Automatic sawing machine

Info

Publication number: EP3493962B1
Application number: EP17761593.7A
Authority: EP
Inventors: Giuseppe Nicoletti
Original assignee: MEC Srl
Current assignee: MEC Srl
Priority date: 2016-08-05
Filing date: 2017-08-04
Publication date: 2021-11-24
Anticipated expiration: 2037-08-04
Also published as: EP3493962A1; WO2018025234A1; IT201600083065A1

Description

Technical field of the invention

The present invention generally relates to devices for cutting blocks of natural stone, such as marble or granite, as well as concrete blocks. More particularly the concerns an automatic sawing machine for cutting said blocks in order to obtain surface coating elements.

Background

Automatic sawing machines for cutting blocks of stone, marble, granite and similar stone materials, or concrete blocks manufactured in cement plants by way of suitable molds, are known and employed for the manufacturing of surface coating elements. These sawing machines typically comprise at least one conveyor belt extending longitudinally and defining a cutting path along which a plurality of cutting devices are consecutively arranged. The cutting devices comprise a motor, for example an electric motor, on whose axis a circular blade, typically a diamond disk, is keyed. The circular blades are aligned transversely to the cutting path so as to define a line for the cutting of the blocks. An automatic sawing machine of this type is e.g. described in the patent publication EP 1103359 A1 .
The cutting devices can be arranged at different heights from the conveyor belt and the circular blades can have diameters different from one another, so that cutting of the blocks can be carried out progressively as they are made to advance along the cutting path.
Also known are automatic sawing machines comprising two conveyor belts disposed at right angles to each other and inclined relative to a horizontal plane, so as to define a channel suitable for receiving blocks to be cut. Thanks to the inclination relative to the horizontal plane, the blocks contact both conveyor belts due to their own weight, which makes it easier to maintain their position during cutting operations. An example of an automatic sawing machine of this type is described in US 2008/236560 A1 .
In order to use cut blocks as coating elements, it is of the utmost importance to make cuts that are as straight as possible. To this aim, the blocks intended to be loaded into an automatic sawing machine are pre-selected so that their respective thicknesses are as homogeneous as possible. More particularly the thickness of each block lies within a predetermined dimensional range.
In addition to this, in order to take into account the variable size and irregular shape of the blocks, locking, centering or positioning devices have been developed among which, for example, a second conveyor belt arranged opposite to the conveyor belt intended to carry the blocks. The two conveyor belts enclose the blocks to be cut in a sandwich like manner. An automatic sawing machine of this type is for example described in the above mentioned publication EP 1103359 A1 . By suitably choosing the hardness, elasticity, thicknesses and other parameters of the materials of which the conveyor belts are made, it is possible to appropriately modify the grip on the blocks to be moved and compensate for their thickness variations.
The Italian patent 1362425 describes an automatic sawing machine that is structurally similar to the automatic sawing machine of EP 1103359 A1 , but wherein centering or positioning of the blocks is carried out by way of a conveyor belt that is e.g. bellows-shaped. According to Italian patent 1362425 , instead of a shaped conveyor belt it is possible to use a centering element consisting of a longitudinal bar on which a plurality of wheels that are individually mounted on harmonic steel strips are consecutively mounted.
The patent US 7056188 B1 describes an automatic sawing machine comprising a frame, a first conveyor belt and a second conveyor belt, wherein said first conveyor belt and said second conveyor belt are arranged at right angles, and a plurality of cutting devices, each cutting device comprising a motor on whose shaft a circular blade is keyed, said cutting devices being restrained to said frame subsequent to each other in said longitudinal direction, wherein said positioning device comprises a bar restrained to the frame in the longitudinal direction of the automatic sawing machine, said bar comprising a plurality of arms pivotally restrained thereto and urged away there from by way of a respective tensioning device, and wherein the conveyor belts are mounted movably relative to the frame.
Despite the various types of automatic sawing machines for cutting blocks of stone, marble, granite and the like, thickness compensation means can handle thickness variations in rather limited ranges, typically in the order of 30- 50 mm, which requires a manual preliminary selection of the blocks.
For this reason, the production costs of surface coating elements are considered by those skilled in the art to be rather high.

Summary of the invention

The technical problem underlying and solved by the present invention is therefore to provide an automatic sawing machine suitable to overcome the drawbacks mentioned above with reference to the prior art.
This problem is solved by an automatic sawing machine according to claim 1. Preferred features of the present invention are recited in the dependent claims.
The automatic sawing machine according to the invention comprises in a known way two conveyor belts that are disposed at right angles to each other and are mounted on a frame or base. The conveyor belts define a channel suitable to receive blocks to be cut. The automatic sawing machine further comprises a device for positioning the blocks to be cut, the device consisting of a bar arranged parallel to the channel, i.e. the cutting path, and of a plurality of arms that are consecutively mounted on the bar. The arms are rotatably restrained to the bar and are urged away from it by tensioning devices, for example spring or pneumatic actuated tensioning devices. The bar of the positioning device is movably mounted perpendicularly to the cutting path defined by the conveyor belts and the conveyor belts are movably mounted relative to the frame.
When the blocks advance along the cutting path, the arms contact them and individually rotate towards the bar, thus compensating for thickness variations of the single blocks as well as thickness variations from one block to another, while at the same time performing positioning of the blocks, which is needed to ensure straightness of the cuts. Thanks to the use of arms pivoted on a bar, and due to the fact that both the bar and the conveyor belts are movably mounted relative to the frame, it is possible to compensate for thicknesses variations within a range of 150-200 mm or even higher, which is much more than what is achievable by the positioning devices of the automatic sawing machines known in the art.
The main advantage provided by the invention is therefore to allow machining of blocks of very different size, which results in a hourly throughput that is higher than what is presently achievable by prior art automatic sawing machines. The related manufacturing costs are thus significantly lower.
The two conveyor belts arranged at right angles to each other may advantageously be mounted on the frame of the automatic sawing machine inclined with respect to a horizontal plane. As it is well known, this facilitates maintenance of the position of the blocks to be machined by exploiting their own weight.
According to an embodiment of the invention, idle or motorized rollers may be advantageously mounted at the ends of the arms intended to contact the blocks to be cut, thereby reducing frictional contact between the ends of the arms and the blocks. The rollers may be made of or coated with rubber.
Another advantage offered by the invention is that, thanks to the possibility of machining blocks having a very different thickness, manual selection operations can be avoided. This also allows to make a manufacturing line comprising at least one stone splitting machine and at least one automatic sawing machine arranged in series, wherein the automatic sawing machine is arranged at an outlet of the stone splitting machine so as to receive from it split blocks to be cut without resorting to manual operations.
According to a preferred embodiment of the invention, the bar on which the compensating arms are restrained is movably mounted relative to the conveyor belts that define the cutting path. Thanks to this configuration, it is possible to adjust the distance between the ends of the arms when they are fully extended and the cutting means, thus allowing to set the machine according to a minimum expected size of the blocks to be machined.
According to an embodiment of the invention, the conveyor belts defining the cutting path are movably mounted on a frame of the automatic sawing machine, thereby allowing to set a desired cutting thickness.
The overall configuration of the sawing machine allows to cut the blocks to be machined not only in order to obtain thin slices, but also elements cut in a half, which offers the possibility to deliver finished calibrated pieces according to current industry needs as well as customers' specific requirements.
A further advantage of the invention is that the cutting devices are movable to and from the channel or cutting path defined by the conveyor belts, thereby allowing to adjust the cutting depth and to progressively cut the blocks as they are made to advance along the cutting path.
Further advantages, features and operation modes of the present invention will become clear from the following detailed description of some embodiments that are presented as non-limiting examples.

Brief description of the drawings

Reference will be made to the figures of the attached drawings, in which:

Figure 1 is a perspective view schematically showing an automatic sawing machine according to an embodiment of the present invention;
Figure 2 shows a detail of figure 1;
Figure 3 is a partial side view of the automatic sawing machine of figure 1;
Figure 4 is a perspective view showing a cutting path of the automatic sawing machine of figure 1 and a device for positioning the blocks to be machined;
Figure 5 shows a detail of figure 4;
Figure 6 is a partial side view of the automatic sawing machine according to the present invention similar to the view of figure 3, but wherein the positioning device has been moved relative to the cutting path and the latter has been moved with respect to the cutting devices of the automatic sawing machine;
Figure 7 is a perspective view showing an arm of the positioning device on which free ends two pairs of rollers are mounted;
Figures 8 and 9 are perspective views similar to that of figure 7 showing different arrangements of the rollers mounted at the ends of an arm of the positioning device;
Figure 10 is a side view showing the arrangement of the rollers according to figure 9;
Figures 11 and 12 are perspective views of the automatic sawing machine showing an arrangement of the arms on the positioning device with the rollers arranged as shown in figures 8 and 9;
Figures 13 to 15 show a further embodiment of the automatic sawing machine according to the present invention.

Detailed description of preferred embodiments

Referring initially to figure 1, an automatic sawing machine according to the invention is generally indicated by reference numeral 100 and is shown in a triaxial reference system wherein a first direction X represents a longitudinal direction of the automatic sawing machine 100 and a second direction Y represents a transverse direction of the automatic sawing machine 100. The directions X and Y define a supporting plane of the machine 100.
A third direction Z of the reference system indicates a vertical direction along which the force of gravity acts.
The automatic sawing machine 100 comprises in a known way a frame or base 110, for example consisting of an electro welded steel structure, on which a first conveyor belt 120 and a second conveyor belt 130 are mounted. The first conveyor belt 120 and the second conveyor belt 130 are both motorized and mutually arranged at right angles.
The conveyor belts 120, 130 may be advantageously inclined with respect to a horizontal plane so as to define a channel, i.e. a cutting path, suitable to receive blocks B to be cut. Such blocks B are held in contact with conveyor belts 120, 130 due to their own weight.
In the following, reference will be made to a configuration of the automatic sawing machine wherein the conveyor belts 120, 130 are inclined with respect to a horizontal plane, but it will be appreciated that this is not a limiting feature of the invention.
The term "blocks" is meant to indicate pieces of natural stone or concrete pieces of any shape, either irregular due to splitting of digging operations or regular when obtained by molding operations.
At the ends of the cutting path in the longitudinal direction X, the automatic sawing machine 100 comprises an inlet portion 111 and an outlet portion 112 that are advantageously provided with a plurality of rollers allowing to ease loading of the blocks B to be machined and discharging of finished pieces and waste.
In the illustrated embodiment, the inlet portion 111 and the outlet portion 112 are aligned with the first conveyor belt 120 and define with it a first supporting plane of the blocks that is e.g. inclined by 20° with respect to a horizontal plane. The second conveyor belt 130 is perpendicular to the first conveyor belt 120 and defines a second supporting plane for the blocks to be machined.
The automatic sawing machine 100 also includes in a known way a plurality of cutting devices 140 every one of which is made up of a motor 141 on whose axis a circular blade 142, typically a diamond disk, is keyed. In the following, reference will be made to diamond disks, but it will be appreciated that they are not an essential feature of the invention.
The cutting devices 140 are restrained to the frame 110 consecutively in the longitudinal direction X and arranged above the channel defined by the conveyor belts 120, 130 relative to the vertical direction Z, so that their diamond disks 142 are arranged in the channel as shown in particular in figures 2 and 3.
In the illustrated embodiment the diamond disks 142 are arranged perpendicularly to the first conveyor belt 120, which is aligned with the inlet and outlet portions, and parallel to the second conveyor belt 130 against which the blocks B are supported due to their own weight during machining.
The cutting devices 140 are movably mounted relative to the channel-shaped cutting path defined by the conveyor belts 120, 130 so that the cutting depth of the blocks B can be adjusted. For this purpose, the electric motors 141 of the cutting devices 140 are restrained to respective moving means, such as mechanical ball screw actuators, that are in turn restrained to the frame 110 of the automatic sawing machine 100.
In addition to this, diamond disks having different diameters may be mounted on the cutting devices 140, which allows a great freedom when setting the cutting depth along the channel.
The automatic sawing machine 100 further comprises a positioning device configured to keep the blocks B in contact with the conveyor belts 120, 130 defining the channel or cutting path and also configured to compensate for thickness variations of single blocks B and between consecutive blocks B.
The positioning device is generally designated by reference numeral 150 and comprises a bar 151 restrained to the frame 110 in the longitudinal direction X close to the cutting path and a plurality of arms 152 that are pivoted on the bar 151 and urged away from it by a respective tensioning device, e.g. spring, piston device or an equivalent one.
More particularly, in the illustrated embodiment the bar 151 is arranged parallel and opposite to the second conveyor belt 130 and perpendicular to the first conveyor belt 120, so that the arms 152 pivoted on the bar 151 are moved parallel to the first conveyor belt 120 to and from the second conveyor belt 130.
When the blocks B are made to advance along the cutting path, the ends of the arms 152 progressively contact them and the arms 152 rotate towards the bar 151 thereby compensating for thickness variations of individual blocks B as well as for thickness variations from a block B to a consecutive one. The bar 151 and the arms 152 also perform a positioning and restraining function necessary to ensure straightness of the cuts made by the diamond disks 142.
It will be appreciated that the use of arms 152 allows to compensate for thickness variations in a wide dimensional range, which is as wide as long the arms 152 are.
At the ends of the arms 151 rollers 153, e.g. made of rubber or rubber coated, may advantageously be mounted. The rollers are intended to contact the blocks B during machining. The use of the rollers 153 reduces the contact friction between the ends of the arms 152 and the blocks B. The rollers 153 may be idle or motorized depending on transport and positioning needs of the blocks and the type of material with which they are made.
Now referring to figures 3 and 6, the bar 151 of the positioning device 150 is movable perpendicularly to the channel defined by conveyor belts 120, 130. To this aim, the bar 151 is e.g. mounted on a plurality of supports 154, for example box-shaped, which are mounted slidably on respective guides 155, for example a pair of guides, restrained to a frame 160 extending in the longitudinal direction X and supporting the first conveyor belt 120 and the second conveyor belt 130 with respective motors. The guides 155 extend perpendicularly to frame 160, i.e. perpendicular to the first and second conveyor belts 120, 130.
Thanks to this configuration, it is possible to adjust the distance between the ends of the arms 152 when they are fully extended and the channel, in particular the second conveyor belt 130, thereby allowing to adjust the machine according to a minimum desired size for the blocks B to be machined.
The conveyor belts 120, 130 defining the cutting path are also movably mounted perpendicularly to the frame 110 of the automatic sawing machine 100, and hence movable relative to the diamond disks 142 of the cutting devices 140, thus allowing to set a desired cutting thickness.
Still referring to figures 3 and 6, the frame 160 includes a slider 161 slidably restrained to a portion 113 of the frame 110, for example on a rail 114 that is in turn mounted to or formed on the portion 113. By moving the frame 160 along the portion 113 of the frame 110, for example by way of a linear actuator (not shown), it is possible to vary the distance between the second conveyor belt 130 and the cutting disks 142, thus allowing to adjust the nominal thickness of the blocks B to be machined.
Now referring to figures 7 to 10, the rollers 153 mounted at the ends of the arms 151 may be arranged in various ways, which provides the advantage of being able to configure the positioning device in the most appropriate manner depending on the type of blocks to be machined.
Figure 7 shows, for example, two pairs of rollers arranged on opposite sides of the arm 152 and pivotally connected to a common axis.
Figure 8 shows an alternative arrangement according to which a plurality of rollers 153, for example three rollers, are mounted on one side of the arm 152 and are arranged rotatably on a common axis.
Figures 9 and 10 show a further alternative arrangement according to which a plurality of sets of rollers 153 rotatably mounted on respective axes, for example three sets of three rollers, are mounted on one side of the arm 152. The three sets of rollers 153 are, for example, arranged at 120° to each other and are mounted on a support 152a pivoted close to the free end of the arm 152. This configuration provides the advantage of allowing not only a rotation of the rollers 153 about the respective axes, but also a rotation of the sets with respect to the arm 152, which offers the advantage of a higher contact with the blocks to be machined and a much more precise and continuous guide.
Still with reference to figures 7 to 10, in order to facilitate assembly of the arms 152 on the bar 151, the arms 152 are advantageously provided with a box-shaped body 156 housing the tensioning device (not shown), such as spring or pneumatic actuated tensioning device, urging the arms 152 away from the bar 151.
The choice of pneumatic tension devices is preferred because they automatically manage the pressure resulting from a force exerted by the arms 152 and the rollers 153 against the blocks B. For this purpose, the sawing machine 100 may comprise a pressure regulator operatively connected to a control system thereof.
The automatic adjustment of the pressure of the air supplied to the tensioning devices also allows to set maximum safety values beyond which air pressure is reduced so as to prevent damage to the positioning device 150 of the sawing machine 100.
The bar 151 of the positioning device 150 comprises a plurality of seats configured to receive the box-shaped bodies 156. Each box-shaped body 156 is provided with means for the assembly to the bar 151. In order to allow assembly to the bar 151 each box-shaped body 156 is provided with e.g. a flange 157 intended to abut the bar 151 and configured to be fixed thereto for example by way of screws, welds or the like. It will be appreciated that the flange is not a binding for the fastening of the box-shaped bodies 156 and that equivalent assembly means known to those skilled in the art could be employed.
Now referring to figures 11 and 12, according to a preferred embodiment of the invention, the bar 151 of the positioning device 150 does not include single seats for the box-shaped bodies 156 of the arms 152, but at least one guide, for example in the form of a longitudinal through groove, along which the box-shaped bodies 156 of the arms 152 may be mounted at a plurality of different positions by choosing the most suitable relative distances depending on the blocks to be cut and also on the position of the arms 152 in the longitudinal direction X. The adjustment of the position is made by moving the box-shaped bodies 156 of the arms 152 along the longitudinal groove formed in the bar 151.
Fastening of the box-shaped bodies 156 along the groove can be carried out, for example, by using the flange 157 and a counter flange 158 which form a clamp suitable to lock the box-shaped bodies 156 by friction.
It is e.g. preferred a to arrange the arms 152 close to each other at the inlet portion 111 or loading area of the sawing machine 100, where the blocks B to be machined are not yet in contact with the diamond disks 142 of the cutting devices 140, as well as at the portions of the cutting path that are arranged between subsequent diamond disks 142, wherein it is very important to keep the position of the blocks B so as to ensure the straightness of the cut. Larger distances among the arms 152 may instead be set in the portions of the cutting path that are arranged at the cutting devices 140, because during cutting the diamond disks 142 also perform a positioning action of the blocks being machined.
The bar 151 of the positioning device 150 may advantageously comprise two or more guides arranged parallel to each other in the vertical direction Z. Hence, the arms 152 may be arranged at multiple levels and also staggered in the longitudinal direction X, thus allowing to obtain a higher contact degree with the blocks B to be machined and a better guidance in the longitudinal direction X, for the benefit of the straightness of the cuts.
In the embodiment shown in figures 11 and 12, the bar 151 includes two longitudinal guides 151a, 151b.
The possibility of using different arrangements of the rollers 153 on the arms 152 offers the additional advantage of being able to configure the positioning device in the most appropriate way to guide the blocks B during machining.
With particular reference to figure 11, in the portion of the cutting path adjacent to the inlet portion 111, the bar 151 comprises a plurality of arms 152 provided with three sets of rollers 153 such as those shown in figures 9 and 10. By proceeding in the longitudinal direction X the bar is provided with a plurality of arms 152 of the type shown in figure 8, i.e. having rollers 153 mounted on a common axis on one side of the arms. Different arrangements may of course be made, for example by alternating the arms 152 shown in figure 8 and figures 9 and 10.
As mentioned above, a close arrangement of the arms 152 is preferred at the inlet portion 111 or loading area of the sawing machine 100, wherein the blocks B to be machined are not yet in contact with the diamond disks 142 of the cutting devices 140. The action of the arms 152 is also important in the cutting path portions arranged between consecutive diamond disks 142 in the longitudinal direction X, where it is necessary to maintain the position of the blocks B in the transverse direction in order to ensure straightness of the cut.
Now referring now to figures 13 to 15, according to a further embodiment of the invention, the sawing machine 100 may advantageously comprise a plurality of guiding members arranged between pairs of diamond disks 142 consecutively arranged in the longitudinal direction X and configured to facilitate passage of the blocks being machined from a diamond disk 142 to a consecutive one, as it will be described in greater detail in the following.
In the embodiment shown in figures 13 to 15, the sawing machine 100 includes for example two diamond disks 142 so that a single guiding member is provided. The guiding member is generally indicated by reference numeral 170.
It will be appreciated that a sawing machine having three diamond disks will have two guiding members 170, a sawing machine having four diamond disks will have three guiding members 170, and so on.
The guiding member 170 comprises a support 171 fixed to the frame 110 of the sawing machine 100 between two consecutive cutting devices 140 and a sheet metal plate 172 that is coplanar with the diamond disks 142, more generally to the circular blades, in the transverse direction and progressively extends from the support 171 and in the longitudinal direction X thus defining a substantially continuous surface in this directions with the diamond disks 142.
The technical effect of this configuration is to create a substantially continuous guide path in the longitudinal direction X for machining the blocks B, in such a way to avoid formation of step-like discontinuities between a cut performed by a diamond disk and a cut made by a consecutive diamond disk.
According to this embodiment of the invention, the arms 152 of the positioning device 150 are strictly necessary only at the inlet portion 111 or loading area of the sawing machine 100, while in the portions of the cutting path sections where the diamond disks 142 are arranged, as well as in the portions between pairs of consecutive diamond disks, the arms may be completely absent as shown in the illustrated embodiment, or possibly present for redundancy reasons, because the guiding function in the longitudinal direction X is essentially carried out by the diamond disks 142 and the guiding members 170 arranged between them.
As discussed above, the guiding member 170 progressively extends in the longitudinal direction X defining a shape suitable to create a substantially continuous surface in this direction with the diamond disks 142. In the embodiment shown in figures 13 to 15, the guiding member 170 has for example two curved portions 173, 174 opposite to each other in the longitudinal direction X and respectively concentric with the two adjacent diamond disks 142. The radiuses of the curved portions 173, 174 are slightly larger than those of the diamond disks 142, so that between the latter and sheet metal plate 172 slits are defined in the circumferential direction. It will be appreciated that this is not an essential feature of the invention and that, for example, the sheet metal plate 172 might comprise opposite straight portions in the longitudinal direction X instead of the curved portions.
According to an embodiment of the invention (not shown), the sheet metal plates 172 of the guiding members 170 may have a telescopic configuration that can be extended vertically and enlarged longitudinally so as to allow to finely adjust their surface area depending on the machining of the blocks B.
The present invention has been disclosed hereinabove with reference to preferred embodiments. It will be appreciated that further embodiments relating to the same inventive idea may exist, all encompassed within the scope of protection of the claims set forth below.

Claims

An automatic sawing machine (100) for sawing natural stones pieces and concrete blocks, said machine comprising:
i) a frame (110);

ii) a first conveyor belt (120) and a second conveyor belt (130), said first conveyor belt (120) and said second conveyor belt (130) being both motorized and mutually arranged at right angles, the first conveyor belt (120) and the second conveyor belt (130) defining in a longitudinal direction (X) a channel-like cutting path suitable to receive consecutive natural stones pieces or concrete blocks (B) to be cut;

iii) a plurality of cutting devices (140), each cutting device comprising a motor (141) on whose shaft a circular blade (142) is keyed, said cutting devices (140) being restrained to said frame (110) subsequent to each other in said longitudinal direction (X) and being arranged above the channel-like cutting path defined by the conveyor belts (120, 130) with respect to a vertical direction (Z), perpendicular to the longitudinal direction (X), so that the respective circular blades (142) are located within the channel-like cutting the path;

iv) a positioning device (150) configured to maintain said blocks (B) in contact with the conveyor belts (120, 130) that define the cutting path during their processing,
wherein that said positioning device (150) comprises a bar (151) restrained to the frame (110) in the longitudinal direction (X) of the automatic sawing machine (100) parallel to the cutting path defined by the conveyor belts (120, 130), said bar (151) comprising a plurality of arms (152) pivotally restrained thereto and urged away therefrom by way of a respective tensioning device, wherein the bar (151) of the positioning device (150) is mounted movably perpendicularly to the cutting path defined by the conveyor belts (120, 130), and in that the conveyor belts (120, 130) are mounted movably relative to the frame (110) and wherein said automatic sawing machine (100) further comprises a plurality of guiding members (170) arranged between pairs of circular blades (142) that are consecutive to each other in the longitudinal direction (X), wherein each guiding member (170) comprises a support (171) fixed to the frame (110) of the automatic sawing machine (100) in the zone comprised between two consecutive cutting devices (140) and a sheet metal plate (172) lying on the same plane of the circular blades (142), said sheet metal plate (172) extending in the vertical direction (Z) and progressively widening in the longitudinal direction (X) from said support (171), the overall configuration of the guiding member (170) being such that the sheet metal plate (172) forms together with the circular blades (142) a surface that is substantially continuous in the longitudinal direction (X)..
An automatic sawing machine (100) according to claim 1, wherein the positioning device (150) further comprises idle or motorized rollers (153) mounted at the ends of every one of said arms (152).
An automatic sawing machine (100) according to claim 2, wherein said rollers (153) are arranged on opposite sides of each arm (152) and are rotatably restrained to a common axis.
An automatic sawing machine (100) according to claim 2, wherein said rollers (153) are arranged on one side of each arm (152) and are rotatable restrained to a common axis.
An automatic sawing machine (100) according to claim 2, wherein a plurality of sets of rollers (153) are mounted on one side of each arm (152) and are rotatably restrained on respective axes, said sets of rollers (153) being mounted on a supporting member (152a) pivotally connected at the end of the arm (152).
An automatic sawing machine (100) according to any one of claims 1 to 5, wherein the arms (152) are provided with a box-shaped body (156) inside which said tensioning device is arranged, and wherein said box-shaped body (156) comprises means configured to allow mounting thereof on the bar (151).
An automatic sawing machine (100) according to claim 6, wherein said tensioning device is a pneumatic actuated tensioning device.
An automatic sawing machine (100) according to any one of claims 1 to 7, wherein the arms (152) are configured so that their displacement stroke to and from the bar (151) is in the order of 150-200 mm or higher.
An automatic sawing machine (100) according to any one of claims 1 to 8, wherein the bar (151) is mounted on a plurality of supports (154) that are in turn slidably mounted on guides (155) restrained to a frame (160) supporting the first conveyor belt (120) and the second conveyor belt (130) with their respective motors, said guides (155) extending perpendicularly to said frame (160).
An automatic sawing machine (100) according to any one of claims 1 to 9, wherein the cutting devices (140) are mounted on the frame (110) movably in the vertical direction (Z).
An automatic sawing machine (100) according to any one of claims 1 to 10, wherein a frame (160) supporting the conveyor belts (120, 130) comprises a slide (161) that is movably restrained to a guide (114) that is in turn attached to or formed on a portion (113) of the frame (110) of the automatic sawing machine (100).
An automatic sawing machine (100) according to any one of claims 6 to 11, wherein the bar (151) of the positioning device (150) comprises at least one guide (151a, 151b) configured to receive the box-shaped bodies (156) of the arms (152).
A processing line for the processing of natural stone pieces and concrete blocks, said processing line comprising at least one stone splitting machine for natural stone pieces and concrete blocks and at least one automatic sawing machine (100) according to any one of claims 1 to 12, wherein said automatic sawing machine (100) is arranged at an outlet of said stone splitting machine so as to receive therefrom split blocks to be cut.