The present invention relates to a screeding machine for leveling floor bases.

More particularly, the invention concerns an improved screeding machine for leveling floor bases, comprising two tracks, parallel to each other, which support and move in two directions a frame or chassis, on which an articulated arm carrying a rotating tool is mounted; moreover, an automatic adjustment electronic system allows to carry out a continuous control of elevation, with respect to a plane generated by a laser projector, so that the accuracy of the plane made with the continuous control of elevation is such as not to affect the essential continuity effect of the plane which is produced, despite the succession of multiple adjacent screeding workings. The floors are generally constituted by sand or cement layers and they may be made with or without foundations.

In particular, the floors with foundations are placed on a foundation screed (also called "cardana-screed"), which is placed and smoothed on the layer to be floored and which is normally a semi-humid mixture of sand, cement and water, in which the concentration of cement is low and the water is dosed as required to obtain a mixture having a semi-dry consistency (a moist-sand mixture), which is able to obtain a product with well defined geometrical characteristics _/ also avoiding the cropping up of plasticity features, that would occur were the mixture was dosed with too much water and which would generate unwanted movements of the mixture during and after the laying oh the floor, and therefore unwanted variations of quality and geometry of the floor plain during and after drying.

The above mentioned mixtures are produced using pre-mixed products or they are manually dosed by the operator.

The mixture, lying on the unfinished floor of the building, with a thickness of about 3-15 cm and smoothed to obtain a finished surface, forms the laying bed on which are placed all types of coating, such as ceramic, marble, parquet, carpet, resins, etc.; a further object of the screed is also to have a space in which to install the water pipes, the electricity cables and/or cables of other services.

The semi-dry mixtures having a thickness of 3-15 cm, in a pasty state, have a compression strength of between 0.05 and 0.15 Kg/cm2 and the operation of screeding said mixtures is mainly composed of the following steps. 1 Firstly, in a first step, the elevation and orientation of the plane is j determined, by defining at least three points for which the plain to be made must cross; during this operation, in order to obtain the above reference points, necessary to define the plain to made, a prefixed elevation, 5 established by the management of the construction yard, located on each floor of the building and used by all professionals (electricians, plumbers, carpenters, floor layers, etc.) as a reference point for the installation of various devices, is used as a reference.

Small islands or points, made using the same material of the screed, are 10 spaced apart, so that an aluminum rod or bar of suitable length rests on at least two of said islands and in such a way that their horizontal plane is placed, with respect to a vertical line (lead line), at a prefixed distance from the reference elevation established by the construction yard.

During a second working step parallel stripes (called bands), suitably 15 spaced, are made with the same mixture material and are manually obtained by using the rod, thus creating a continuity of the plane among the points which are previously determined.

During a third working step the mixed material is placed within the parallel strips or bands, which have been previously made, while during a fourth 0 working step the so-called leveling operation is made, i.e. an operation according to which a kneeling operator swipes the rod on the bands to remove the excess material, placed between the bands during the previous step, in order to create in this way a single and continuous plane. Such leveling operation may also be performed with suitable appropriate 5 mechanical equipment, such as bridge screeding machines of the type described for example in EP1163408B1 , in which respective carriages move forward on lateral guides and are connected to two sections, belonging to the bridge structure, which are sliding on each other and one of which is fixed to a mechanical structure supporting a milling cutter; a o suitable combination between the motion of rotation of the cutter (which rotates in a direction depending on the direction of the side carriages) and the motions of the carriage supporting the milling cutter and of the side carriages of the machine allow to automatically obtain a displacement and compression of the screed up to an appropriate optimal leveling.

5 In a further processing step it is possible, by means of a manual trowel or by means of a suitable mechanical equipment, to tamper the foundation and to smooth and level the screed, in order to obtain a homogeneous and leveled plain (which allows to obtain a screed which is less porous and which can absorb less adhesive during the coating material laying step). However, the above known operations which can be made for leveling the screed have several drawbacks, including the drawback consisting in having to position the screeding machine in correspondence of the screed to be leveled, for each portion of the foundation which has to be processed.

Furthermore, such operations, whether they are manual or realized by means of known screeding machines, however, give a screed which is not perfectly flat, but undulating, as the only reference for the operator is the same plane on which the machine or the manual trowel leans.

An object of the present invention is therefore to overcome the above technical drawbacks and, in particular, to indicate a screeding machine for leveling floor bases, which can be moved, simply and quickly, directly on the screed of the foundation, without having previously made supporting guides or bands, for the entire surface to be leveled, when the material of the screed is yet in a mixture and in any case before the beginning of the curing effect due to drying.

Another object of the present invention is to provide a screeding machine for leveling floor bases, which allows to obtain, simply and by a single operation, a surface layer of the screed, which is smooth, suitably compressed and perfectly leveled in a plane, without making a tamping operation, in correspondence with the entire surface to be walked on or to be floored and for every type of material used as foundation.

Another object of the present invention is to provide a screeding machine for leveling floor bases, which allows to drastically reduce the processing times and the floor installation costs, with respect to the prior art.

A further object of the invention is to provide a method for making floor foundations, which is provided by means of the above mentioned machine.

These and other objects, which will become apparent in the following discussion, are achieved by a screeding machine for leveling floor bases, according to the appended claim 1 ; further detailed technical features are also contained in the dependent claims.

Advantageously, it is enough to place the mixture of the screed over the entire surface to be floored and operate the screeding machine, in order to obtain, by means of a single processing step and regardless of the size and geometry of the surface, a layer of screed having a desired thickness, compact and perfectly leveled and flat, so that the subsequent laying of the floor is perfectly flat and/or without undulations, disconnections, cracks or depressions.

Moreover, the screeding machine has a size that can pass through all the interior doors of the flats, and this feature allows to not have to lift and move manually the machine to go through the rooms,, but to continue the work through the passage of the doors and to pass in the hallways with continuity.

Further characteristics and advantages of the screeding machine for leveling floor bases, which is the object of the present invention, will become clear from the description of a preferred and illustrative, but not limiting, embodiment of the machine, and from the alleged drawings, wherein:

- figure 1 shows a front perspective view of the screeding machine for leveling floor bases in a first operating position, according to the present invention;

- figures 2, 2A and 2B show, respectively, two partial side views and a partial below perspective view of the machine of figure 1 , according to the present invention;

- figure 3 shows a partial perspective view of the machine of figure 1 ;

- figure 4 shows the enlarged detail A of figure 3, according to the present invention;

- figure 5 shows a front perspective view of the machine of figure 1 , in a second operating position;

- figure 6 is a total side view of the machine of figure 5;

- figure 7 shows the enlarged detail B of figure 6, according to the present invention;

- figure 8 is a front view of the machine of figure 1 , according to the present invention;

- figure 9 is a top plan view of the machine of figure 1 , according to the invention;

- figure 10 shows a schematic diagram in a further operating position of the machine, according to the present invention;

- figure 11 shows the enlarged detail C of figure 10, according to the present invention;

- figure 12 is a top perspective view of the machine of figure 1 , in the operating position shown in figure 10, according to the present invention;

- figures 13 and 14 show further operation diagrams of the machine according to the invention;

- figure 15 is a partial side view of the machine shown in figure 5, according to the present invention;

- figure 16 shows the enlarged detail D of figure 15, according to the present invention;

- figures 17, 18, 19, 20 and 21 show perspective exploded and sectional views of a portion of the machine shown in figure 5, according to the present invention;

- figure 22 is a top plan view of the portion of the machine shown in figures from 17 to 21 , according to the present invention.

With reference to the mentioned figures, the screeding machine for leveling floor bases, which is the object of the present invention, has two tracks AA, parallel to each other, which directly move on the screed to level and which support and move in at least two directions the machine frame or chassis BB, on which an articulated arm CC is mounted; moreover, a turret or adjusting device DD is associated in turn with said articulated arm CC and has, as a terminal element, a rotary tool EE.

During the moving forward and back of the machine, the overall weight of said machine weighs on the screed in correspondence of the total area of the tracks AA, each of which resting on the sliding blocks B1 , being moved by the drive roller A1 and also having an idle roller D1 , a tensioning roller E1 and a belt F1 (as shown in figures 1 , 3, 4 and 5).

The drive roller A1 transmits the motion to the belt F1 , which rotates on the idle roller D1 and on the tensioning roller E1 and leans on the sliding blocks B1 , so that the tangent of the drive roller A1 is the continuation of the tangent of the idle roller D1 (Figs. 3-4); furthermore, the quick displacement of the idle roller D1 make easier the assembly and dismantling operations for maintenance and/or replacement of the belt F1. In particular, the size of the belt F1 contact surface of each track AA between the sliding blocks B1 is such that the track AA makes a specific pressure on the screed below at least a value of between 0.05 and 0.15 Kg/cm2, as the pasty semi-dry mixtures, which constitute the screeds having varying thicknesses between 3 and 15 cm, have a resistance to compression between the values 0.05 and 0.15 kg/cm2; this allows the machine to directly move on the screed that the same machine makes, without sinking into the screed substrate and/or leave traces on the screed.

The machine also includes a plate C1 , positioned below the machine frame BB and between the tracks AA (figs. 2, 2A, 2B), whose size is such that the specific pressure produced on the screed is less than at least a value in the range 0.05-0.15 kg/cm2; the plate G1 can also be translated, projecting beyond the plane defined by the tracks AA of a predetermined measure FF, in order to lift the entire machine frame BB and to move the lower surface of the belt F1 of the tracks AA away from the screed surface during the direction changes of the machine (in fact, the direction change takes place by performing a mechanical rotation of the machine frame BB, which, during the lifting, does not make any pressure and/or material slaver on the finished screed).

Moreover, the machine is extremely easy to handle, since, because the axis of rotation of the plate C1 passes through the center of gravity of the machine frame BB, the lowering of said plate C1 beyond the lower surface of the tracks AA and the subsequent mechanical rotation of the machine frame BB allows to orient the above machine in all directions, including the possibility to make a complete rotation of the machine itself.

The plate C1 is associated with a first reduction gear RI2, which in turn is mounted on a lifting bridge PS; moreover, the lifting bridge PS is associated with two articulations SN1 , SN2, mounted on respective shafts AL1 , AL2, so that a second reduction gear RI1 rotates the first shaft AL1 , which, through a tie rod TR, produces the rotation of the same angular amount of the second shaft AL2.

Thus, the rotation of the shaft AL1 , by means of the reduction gear RI1 , causes a displacement of the joints SN1 , SN2, which, in turn, move the lifting bridge PS and, consequently, the plate C1 , while the reduction gear RI2 causes the rotation of the plate C1 and then the orientation of the camera body BB and of the whole machine (see in particular figs. 6, 7, in which plate C1 is in a rest position, and figs. 15, 16, in which the plate C1 is moved in a vertical direction by a quantity H to rest on the screed) The articulated arm CC is able to move the adjustment turret DD and the attached tool EE on a straight line GG which is parallel to the line HH, the latter joining the joints J, K which connect the articulated arm CC to the machine frame BB (figs. 13-14).

The movement of the articulated arm CC, starting from a rest position, according to which the overall dimensions of the arm CC, of the adjustment turret DD and of the tool EE is included in a cylinder M which contains the whole machine (figs. 8-9), allows the tool EE to run a distance, along the line GG, which is equal to the distance X+Y, moving the weight of the tool EE, of the adjustment turret DD and of the same articulated arm CC near the center of gravity of the machine frame BB (Figs. 13-14); the distances X, Y and X+Y are adjustable and in any case the distance X+Y is greater than the overall width U of the machine frame BB, while the tool EE has overall dimensions greater than any other mechanical device for supporting the adjustment turret DD (which thus has a width smaller than the tool EE overall dimensions of at least a quantity ^z )-

Furthermore, the articulated arm CC is formed by two parallelograms having sides, respectively, E, L, N, 0 and P, Q, R, S, where the lengths of the arms E, L, P and Q are equal, the length O is equal to the length N, the length of R is equal to the length S and the joints 1 , 2, 3 and 4 of the arms E, L, P, Q are positioned on a same straight line JJ; under these conditions, the straight line GG passing through the joints 5 and 6 of the arms P and Q on the turret DD is always parallel to the line HH passing through the joints J, K of the arms E, L on the machine frame BB and the distance KK between the lines JJ and HH changes when the angle a varies (a is the angle comprised between the arm E or L and the straight line LL perpendicular to the lines JJ and HH), since KK=cos a (see figures 10, 11 and 12 for details).

The cross-bar T1 of the articulated arm CC is bound to the arms E, L at a distance F from the joints 1 and 4 of the jointing cross-bar MM and the cross-bar T2 is bound to the arms P and Q at the same distance F from the joints 2 and 3 of the jointing cross-bar MM, while the upright G of the articulated arm CC is bound to the cross-bar T1 and is equipped with a linear guide YL on which the cross-bar T2 slides.

The angular variation a between the arms E, L and the straight line LL, which is perpendicular to the jointing cross-bar T2, causes a displacement of the cross-bar T1 with respect to the jointing cross-bar MM and the cross-bar T1 transmits to the cross-bar T2, via the guide YL, the same displacement.

However, since the cross-bar T2 is bound to the arms P and Q, the same cross-bar T2 will cause on said arms P and Q an angular displacement which is equal to said angle ά variation; practically, an angular movement of a predetermined angle a of the arms E, L cause the same angular movement of the same angle a of the arms P and Q and, therefore, the straight line DD is spatially parallel to the line HH (while the plane containing the straight line HH is parallel to the contact surface NN of the tracks AA on the screed).

Finally, the angular movement of the arms E, L is generated by the angular movement of the sprocket TR, which is associated with the crossbar T3 of the articulated arm CC, said cross-bar T3 being parallel to the cross-bars T1 and T2 and to the jointing cross-bar MM; since the angular sprocket TR is driven by a gear motor, the movement of the entire articulated arm CC can be stopped in any position, including the useful position which meets the conditions relating to the rest position and to the displacement of the total weight of the tool EE, of the adjustment turret DD and of the arm CC near the center of gravity of the machine frame BB.

The adjusting turret or device DD allows to have a continuous control of the tool EE elevation, with reference to a plane generated by a laser projector of a known type, and the precision of the plane realized with said elevation continuous control is such as not to affect the essential effect of continuity of the screed, despite more adjacent workings that the screeding machine is able to perform.

The elevation control is carried out by using at least 3 sensors SE, placed on the same plane PR and oriented and spaced from each other by 120°, which are able to receive the radiation produced by a laser source coming from any direction (as shown in detail in figs. 20-21-22).

Since the laser projectors of the traditional type generate a plan which has a variable thickness (between 2 and 10 mm), depending on the distance between the laser source and the point of reading (unlike an ideal plane which should have a zero thickness), the adjustment turret DD allows to achieve appreciable levels of accuracy (of the order of tenths of a millimeter) for making a floor base (for making a floor base one cannot accept differences of 2-1 mm between a plurality of points that are adjacent and/or close together) using the above mentioned sensors SE. In fact, each sensor SE measures the change in intensity of the laser radiation through the thickness of the plane produced by the known laser projector and the diagram of the intensity of radiation V as a function of the elevation W has a shape that is instrumental^ detectable. Therefore, by analyzing the radiation peak and by developing a calculation system able to estimate the two semi-areas AR1 , AR2 of the peak, it is possible to obtain the direction according to which the sensor SE is to be moved, by calculating the elevation variable W (corresponding to the radiation peak), assuming that AR1=AR2 and taking into account the fact that the intensity of radiation V, the direction of movement of the sensor SE and the elevation variable W appear in the integral calculation of the areas AR1 and AR2.

In this way, the system is suffering neither the thickness of the radiation plane produced by the laser nor the intensity of the laser radiation.

Thus, a microprocessor control system processes the information coming from the sensors SE and generates a command for activating the motor MT of the turret DD to adjust continuously the elevation so that the tool EE carries out the working that is provided and is able to create a screed which is perfectly flat.

In particular, the motor MT rotates a worm VI, which rotates inside a spiral CH producing a displacement of the body PP with respect to the support QQ; the body PP is associated, by means of the middle body RR and the spindle SS, with the tool EE, while the support QQ is integral to the terminal joints 5 and 6 of the arms P and Q on the turret DD frame (figs. 17-18-19). Therefore, the displacement of the tool EE is always referred to the plane of contact NN between the tracks AA and the screed of the floor. Said screed is thus substantially made using the following method.

At first, a known-type laser, equipped with a support, is positioned at a prefixed elevation and oriented according to a desired plane where the screed will be built, also with reference to the plane determined by the construction yard.

Now, the screeding machine object of the present invention, by means of a milling operation obtained by combining the speed of the rotary tool EE, its rotation versus and the shifting of the articulated arm CC, as well as through a height continuous control of said tool EE which is made by means of the adjustment turret DD, is able to produce a plane always parallel to the reference plane previously determined by the laser source. The rotation speed of the tool EE, which is programmable according to the invention, generates a relative speed between said tool EE (a rotary cutter) and the screed, such as to obtain a surface finishing whose accuracy is extremely higher than what it could be achieved by a manual or mechanical tamping operation.

Therefore, using the machine object of the invention, it is not necessary to realize the parallel bands that allow to create a plane continuity according to the prior art, as well as it is not necessary to distribute the mixed material within the bands, as the filling operation is replaced by a simple distribution of the mixture on the screed in a necessary amount.

Moreover, the milling operation made by the screeding machine replaces the traditional operation of leveling a floor base, thus considerably improving the accuracy of flatness of the screed.

Finally, since, using the machine according to the invention, the finishing operation is made at the same time of the milling operation and is always obtained with a continuous control in the plane determination, it is possible to completely avoid all the inaccuracies due to a mechanical or manual finishing operation; furthermore, the geometry of the cutter generates rotary force torques, whose resultants produce a localized pressing of the screed at the same time the displacement of the mixed material, during the screed processing.

The invention thus conceived is susceptible of numerous modifications and variations, all falling within the inventive concept of the appended claims; also, all the details may be replaced by other elements which are technically equivalent, and ^! finally the used materials, provided they are compatible with the specific use, as well as the dimensions may be any according to the requirements and with respect to the state of the art.

Where the features and techniques mentioned in any claim are followed by reference signs, said reference signs have been included for the sole purpose of increasing the intelligibility of the claims and, accordingly, such reference signs do not have any limiting effect on the interpretation of each element which is identified by way of example by such reference signs.