Although all floors must basically perform the same functions, numerous types of flooring are used which vary in terms of construction materials and techniques and in terms of support structure, use, environmental characteristics, intensity and type of traffic, speed of installation, cost, heat and sound insulation, resistance to acids, etc.

Floors can basically be divided into clay or cement floor bases, floors on foundations and floors without foundations.

Clay floor bases are now made by beating and tamping a roughly 30 cm thick layer of preferably clayey soil energetically by hand, using blocks of wood with handles; the operation is performed on successive layers approx. 10 cm thick, and the soil is wet with aqueous binding solutions to increase the compactness of the floor.

Cement flooring is quite commonly employed when particular strength is required; it is consequently used for warehouses, industrial buildings, basements and the like, and can be laid on flat structures or directly on the soil of a basement, with the interposition of a crawl space consisting

of loose stones or arches through which air can circulate freely.

A cement floor base consists of a layer of lean cement concrete beaten and levelled by hand, approx. 10 centimetres thick, finished with a trowel, and a top wearing layer consisting of sand and cement mortar approx. 1-2 centimetres thick.

Alternatively, all varieties of floors on foundations currently on the market rest on a base course approx. 2-4 centimetres thick which is spread by hand on the structure to be floored and levelled well, usually with screeds; the base course is normally constituted by mortar made of sand (fairly thin and not exceeding 3 millimetres) and cement; sometimes lime mortar is used instead of cement mortar to achieve more effective binding to the floor foundation.

Floors on foundations are sub-divided into: (i) homogenous floors obtained by laying a layer of paste material on the foundation which produces a continuous, uniform surface subsequently divided into slabs and then smoothed; and (ii) sectional floors which only differ from the homogenous type in that they are sent to the site from factories which manufacture them in sections ready for laying; in the latter case, a thin layer of cement

mortar is spread on the floor foundation and the elements constituting the flooring are laid on top of this layer, sometimes mixed with special adhesives, so as to produce various types of floor which differ in terms of the size of the elements or the materials used (natural or artificial stone, stoneware, wood or cork, linoleum, rubber, vinyl materials, non-woven or smooth-surfaced wall-to- wall carpeting, or elastomers).

In each case, the preparatory floor base or floor foundation is levelled manually with spirit levels or screeds by one or more workers who must continually check its consistency and thickness, which must be as even as possible, largely on the basis of their skill and experience.

This method presents a number of characteristic drawbacks which are inevitable in manual work, including imprecise smoothing, which leads to imperfect laying of the flooring, long working time and high installation costs. Bearing in mind the fact that the final construction of a floor is determined wholly by the degree of compression and smoothing of the material used in the floor base or foundation, the importance of obtaining suitable physical and mechanical characteristics by preparing the base on which the floor will rest is

obvious.

The object of the present invention is therefore to eliminate the drawbacks of the prior art mentioned above, and in particular to indicate a screeding machine suitable for the construction of floor foundations which produces a smooth, suitably compressed, perfectly flat base layer simply, rapidly and automatically.

In particular, the machine in accordance with the invention is designed to level and flatten all materials used in the construction of floor foundations designed as wearing surfaces or for covering.

Another object of the present invention is to indicate a screeding machine suitable for the construction of floor foundations that produces good results with all types of material used as the base or foundation for floor laying.

An additional object of the invention is to provide an automatic screeding machine suitable for the construction of floor foundations.

A further object of the invention is to provide a screeding machine suitable for the construction of floor foundations which considerably reduces working time and the cost of installing a floor compared with known techniques.

These objects are achieved by a screeding machine suitable for the construction of floor foundations as described in claim 1.

Advantageously, it is sufficient to lay the base mix on the structure to be floored and activate the machine, which can be adapted to the size of the room, in order to obtain a compact, perfectly levelled layer of material with the desired thickness, so that the flooring laid over it is flat and/or presents no interruptions or cracks between the various elements.

The material moved by the machine, which gradually accumulates, can be eliminated during work or after a preset accumulation time, thanks to the fact that the machine can be fitted with a device designed to stop the working cycle automatically after a preset time.

Additional objects and advantages of this invention will become clear from the following description and the annexed drawings, supplied by way of example but not of limitation, in which: -figure 1 shows a perspective view of a first embodiment of a screeding machine suitable for the construction of floor foundations in accordance with this invention, during its operation; -figure 2 shows a front view of the screeding

machine in accordance with this invention in the closed position; -figure 3 shows a front view of the screeding machine in accordance with this invention in the open position; -figure 4 is a cross-section along line IV-IV in figure 3; -figure 5 is an exploded view of the components of the screeding machine in accordance with this invention; -figures 6A-6H illustrate a set of preferred forms of embodiment of the geometry of cutters used in a screeding machine suitable for the construction of floor foundations in accordance with the present invention; -figure 7 shows a perspective view of a second embodiment of a screeding machine, in particular for the construction of floor foundations, according to the present invention; -figure 7A is a perspective view of a portion of the screeding machine of figure 7; -figure 7B is a schematic view of the kinematism of the screeding machine of figure 7; -figure 7C is a sectional view along the line VII- VII of figure 7; -figure 8 is a side view of a first embodiment of

one of the components of the screeding machine of figure 7; -figure 9 is a side view of a second embodiment of one of the components of the screeding machine of figure 7.

With reference to the figures 1-6, the screeding machine suitable for the construction of floor foundations 100, in accordance with this invention, comprises a frame constituted by two parallel guides 10,11 which rest on prefixed references, the said guides being installed at a certain distance apart; each carriage 12,13 runs on each of the said guides and it is fitted with wheels, respectively 18,19 and 191.

The two guides 10,11 constitute the tracks along which the machine moves under operating conditions and have the same thickness, which is uniform along their whole length.

Carriage 13 is associated with a body or beam 15, made of extruded aluminium structural sections; the said beam 15 contains two linear guides 24,25 with two sliding carriages 26,27.

A further beam 14 can slide along structural section 15, guided by the guides, and can be locked onto the said body 15 by a clamp 20 in a closed position of the machine, shown in figure 2, or an

open position, shown in figure 3, or in any other intermediate position required between the said extreme positions, depending on the size of the area to be floored; machines can in any event be made with various widths, in terms of the length of axis X which passes along the centre distance of wheels 18,19 and runs between guides 10,11 in the various machine open or closed positions.

An electric motor 22, connected to reduction gear 23 and to an articulated linkage, which is illustrated in figure 5 and will be described in detail below, controls the rotation of a cutter 16, the traverse of an L-shaped structure 17 associated with the cutter 16, and the rotation of wheels 18, 19,191 of carriages 12,13; inside the body 14 there is a telescopic joint 21 designed to transmit the motion of wheel 19 to wheel 18, whatever the mutual positions of beams 14,15.

Wheel 191 of carriage 13 is idle, and therefore not motor-driven, while the cutter 16 can be adjusted with respect to its height.

Extruded aluminium structural section, which constitutes the beam 15, houses linear guides 24, 25 with their respective sliding carriages 26,27 which are connected to one other via shaped supporting structure 17.

A pin 28 is fitted to shaped structure 17, and a mandrel 29, integral with friction gear 30, rotates around the said pin by means of a set of bearings 32; the said friction gear is counteracted by wall 31. When carriages 26,27 traverse, friction gear 30 causes cutter 16 to rotate in a direction which depends on the direction of traverse of carriages 26,27.

Finally, reference 33 indicates the cap of cutter 16 made of press-mounted hardened metal, and reference 34 indicates the fixing screw of cutter 16 which allows the height of cutter 16 to be adjusted in order to compensate for wear caused by the work performed.

With particular reference to figure 5, it is possible to note that the operation of the screeding machine suitable for the construction of floor foundations 100, in accordance with this invention, is basically as follows.

Electric motor 22 transmits motion to toothed pulley 50, which rotates around axis Y and is connected to structure 17 via cog belt 35 so as to make carriages 26,27 traverse; reduction gear 23, whose axis Z coincides with the axis of a sensor device 36 connected to an actuator or"micro"37, is fitted perpendicular to axis Y.

Sensor 36 is timed to control micro 37 when carriage 26,27 is at the limit of its travel (positions A and B in figure 5), while micro 37 is designed to reverse the direction of rotation of motor 22 in order to produce a to-and-fro motion of carriage 26,27.

An electronic inverter not illustrated in the figure is also installed to make the motion of carriage 26,27 as uniform as possible, control reversals of movement, and drive decelerations, stoppages and accelerations, which take place, under applied torque control, in the proximity of magnetic sensors of a limit switch.

Axis Z is integral with the axis of rotation of pulley 38, which, via double-toothed belt 39, transmits motion to toothed pulley 40, which moves in the same direction of rotation as pulley 38; pulley 38 transmits motion to pulley 42 which moves in the opposite direction of rotation to pulleys 38,40 and 41. The outer part of free wheels 43,44 is integral with pulleys 40,42, and the inner part with shafts 45,46.

As the characteristic of free wheels 43,44 is to transmit motion to the inner part in only one direction of rotation and remain idle in the opposite direction of rotation, and as the two free

wheels 43,44 are simultaneously engaged but with opposite directions of rotation, in the linkage illustrated in detail in figure 5 when wheel 43 transmits motion to shaft 45, wheel 44 makes shaft 46 idle.

Conversely, when motor 22 reverses the direction of rotation, pulleys 38,40 and 42 also reverse their direction of rotation, and wheel 43 will therefore be idle, while wheel 44 transmits motion to shaft 46.

Finally, pulleys 47,48 are integral with shafts 45,46 respectively and are both able to turn cog belt 49 which, in turn, transmits rotatory movement to pulley 51, which is integral with wheel 19 of carriage 13, via shaft 52.

Shaft 45 is integral with telescopic joint 21, which transmits motion to pulley 53 via shaft 54, to pulley 55 via cog belt 56, and consequently to wheel 18 of carriage 12 via shaft 57.

Thus support structure 17, connected to guides 24, 25 of carriages 26,27, allows forward and backward traverse along the beam 15 between points A and B of cutter 16 on belt 35, which is constrained to cutter 16 by support structure 17 and moved along axis Y by pulley 50, which said pulley is connected to motor 22 via belt 60; the linkage used also

produces the effect that when motor 22 and reduction gear 23, controlled by sensor 36 and micro 37, reverse their direction of rotation in proximity to each end point A, B of beam 15, wheels 18,19 of carriages 12,13 which advance beam 15 are always able to rotate in the same direction.

The screeding machine, in particular for the construction of floor foundations according to the invention, works in the following way.

Initially, carriages 12,13 are positioned in correspondence with each end of guides 10,11 (positions C, D in figure 1) previously levelled to obtain the desired surface; after body 14 has been adjusted on structural section 15 with locking clamp 20, the material to be levelled is placed inside the frame located between guides 10,11 in the area to be levelled and smoothed.

When the machine is switched on, carriages 12,13 advance on guides 10,11 in the direction shown by arrows F in figure 1, simultaneously with a traverse of cutter 16 on body 15 from point A to point B in the direction determined by arrow G in figure 1, and cutter 16 rotates in the direction shown by arrow H in figure 1.

Subsequently, during continuous advance of carriages 12,13 along direction F, cutter 16 moves

to and fro along the route from A to B on body 15 so that a traverse in the direction shown by arrow G corresponds to a rotation around its own axis in the direction shown by arrow H, while a traverse in the direction shown by arrow L corresponds to a rotation around its own axis in the direction shown by arrow M.

It will be noted that optimum movement and compression of the material to be levelled, effected by tamping performed by the side walls of cutter 16 and in particular by side area 33, is obtained when the said motions of advance F, traverse G, L and rotation H, M are suitably combined so that the mix to be laid as floor base or floor foundation 100 gradually accumulates in the area of the frame jutting out over body 15 from the side of advance in direction F of carriages 12, 13.

In particular, during a traverse of rotating cutter 16 from A to B in the direction shown by arrow G, the movement of carriages 12,13, namely the distance covered from a fixed point identified on synchronous wheels 18 and 19, does not exceed half the base diameter DB of cutter 16 if the said cutter 16 has a basically cylindrical shape and rotates around its own axis K.

An alternative solution is offered whereby the advance of carriages 12,13 in the direction shown by arrows F, equal to the quantity mentioned above, only takes place when cutter 16 is positioned in correspondence with each end stop A, B.

The cylindrical shape of cutter 16 is shown by way of example of a preferred embodiment but not of limitation. Other examples of geometrical shapes usable for particular types of mix to be levelled and certain degrees of desired compression are shown in figures 6A-6H; however, any polyhedral shape able to give excellent results in terms of movement and compression of the material and smoothing of the surface could be used.

In this respect, it should be noted that the special geometry of the side surface of cutter 16, indicated schematically by the letter S in figures 6A-6H, is responsible for the movement of the material, while any chamfer thereof, with an acute or rounded angle, usually in correspondence with the lower zone 33 and indicated as P1 in figures 6A, 6C, 6E and 6G and P in figures 6B, 6D and 6F, compresses the material to a greater or lesser extent.

Lower surface T smooths the upper surface of the material to be levelled.

Angles a and P, which vary between-90 and +90 sexagesimal degrees on the basis of the degree of compression and the type of material or mix to be levelled, are shown in figures 6A-6H, relating to non-cylindrical cutters 16.

In the case of polyhedral cutters 16 like those shown by way of example in figures 6A-6H, in order to obtain the same results with the material to be levelled as those obtainable with cylindrical cutters 16, the following condition must be met: during traverse of cutter 16 from point A to point B, carriages 12,13 must advance by a linear movement equal to or less than half the base diameter DM (namely the distance between two extreme points of the outer geometry of cutter 16, situated on the same plane), or more generally equal to or less than half the diameter DM of the circumference described by one or more bodies 62 which rotate around axis K of cutter 16.

As shown in detail in figure 6H, cutter 16 could consist of at least one arm 61 which rotates around axis K (corresponding to the axis of rotation of cylindrical cutter 16) to describe a circumference of diameter DM, and is fitted at one of its ends 63 with one or more cylindrical or polyhedral bodies 62 which rotates around its own axis J.

A preferred embodiment of the screeding machine is shown in figures 7,7A, 7B, 7C, wherein the structures which are identical to those of figures 1-5 are indicated with the same reference numerals. In this case, the two beams 14,15 contain the linear guides 241,251 along which the carriages 261,271 are moved, said carriages being associated with two shaped structures 171.

The beams 14,15 are integral with two clamps 201 which allow the beams to be translated, locked and remain parallel; this is possible in all the open conditions of the machine in order to operate in all the width included between the guides 10,11.

The carriages 261,271 house a pin 281 on which a mandrel 293 is made to rotate; the rotation of the mandrel 293 is guaranteed by the transmission belt 290, which is operated by the pulley 291, said pulley being integral with the shaft 292 on which two friction gears 301 are mounted.

The gears 301 generate a rotational movement of the shaft 292 and of the mandrel 293 by means of a friction with the walls of the beams 14,15 in proximity of the reference numerals 293,294. Said friction is a consequence of the translation of the carriages 261,271 and of the shaped structure 171.

The electrical motor 221 moves the toothed belt 351

which, in association with the slidable carriages 261,271, make said carriages to translate until two limit switch magnetic sensors P, Q are engaged. Said sensors render the movement of the motor 221 opposite, thus generating an alternate movement of the group of carriages 261,271 with a consequent rotation of the cutter 16.

A reduction gear 231 makes the shaft B1 to rotate, said shaft, in association with two chains Cl, D1, causing a simultaneous rotational movement of the two wheels 18,19 and the machine to advance on the guides 10,11 along the directions of the arrows F.

By inverting the rotational movement of the reduction gear 231, the screeding machine will move in the opposite direction.

As in the screeding machine disclosed hereinabove, the distance covered by the screeding machine on the guides 10,11 is due to an electronic inverter which is capable of selecting and maintaining a desired number of cycles of the reduction gear 231 under the condition of torque and acceleration control.

The combination of the translation movement of the beams 14,15, according to the arrows G, L, with the movement of the cutter 16, according to the arrows H, M, is a necessary condition in order to perform

the work of the screeding machine in accordance with the present invention.

The translation kinematism of the group of carriages 261,271 and of the shaped structures 171 is shown in particular in figures 7A-7B, from which it is apparent that the electrical motor 221 make the toothed belt 351 move. On the shaft of the electrical motor 221 a toothed pulley K1 is mounted.

The toothed belt 351 has a tortuous path which is caused by the position of the pulleys K1, K2, K5, K4 and K3; in particular, the pulleys K1 and K3 are integral with the beam 15, whereas the pulleys K2, K5 and K4 are integral with the beam 14.

The diameters of the pulleys K1-K5 and their positions meet the geometrical conditions of parallelism among the segments A2-B2, D2-C2, E2-F2, G2-H2 and the axis X2 and Z2, wherein A2, B2, C2, D2, E2, F2, G2, H2 show the tangential points of the pulleys K1-K5 with the corresponding path segments of the belt 351.

Furthermore, the segment A2-B2 must include the point Y2 which is placed on the axis N2 of the cutter 16 and of the carriage 271 and passing through the path A2-B2 of the belt 351. The segment L2, i. e. the distance between the centre of the

pulleys K3 and K4, must be higher than or equal to the maximum translating distance of the beam 14 with respect to the beam 15.

The above mentioned geometrical conditions assure that, when the segment A2-B2 varies of a certain measure, the segment L2 varies of the same measure and therefore the overall length of the belt 351 remains unchanged.

According to this embodiment of the present invention, it is also possible to mount the motor 221 directly on the pulley K1 in order to move the transmission toothed bent 351 without any further electrical connections that may affect the machine inside the working area and limiting said connections to those which connect the motor 221 to the feeding line.

In the embodiments disclosed hereinabove, the rotating cutter 16 is associated with a rotating trowel N, which can also be regulated with respect to its distance from the foundation 100 of the floor; said regulation can be independent with respect to the adjustment of the cutter 16.

Furthermore, the rotating trowel N is placed parallel to and behind the cutter 16, with respect to the frontal view of the machine.

The use of the trowel N, which can be used either

alone or in combination with the cutter 16, allows to get a further final action on the floor foundation 100. For instance, if the trowel N is positioned at the same height of the cutter 16, as shown in figure 8, it allows to collect any residues of material which can erroneously fall beyond the middle part of the cutter 16; alternatively, if the trowel N is positioned below the cutter 16, as shown in figure 9, it allows to get a further compression of the material of the floor foundation 100. Said compression of material turns out to be equal to the distance C3 of figure 9.

In case the trowel N is not mounted, the material in excess must then be manually drained from that area; in this situation, the machine can work according to an alternate working cycle with fixed time intervals in order to periodically drain the material in excess.

The characteristics and advantages of the screeding machine suitable for construction of floor foundations forming the subject of this invention will be clear from the above description.

It is to be understood that numerous variations may be incorporated into the screeding machine suitable for the construction of floor foundations forming

the subject of this invention without departing from the principles of novelty inherent in the invention concept, and that in the practical embodiment of the invention the materials, shapes and sizes of the details illustrated could be modified in any way whatever, depending on requirements, and replaced with others that are technically equivalent.