BACKGROUND ART Casting concrete for the construction of surfaces usually takes place manually, employing at least a pair of workers. The workers use a tool constituted by a blade and by a handle fastened to the blade to operate it. Such a way of operating requires very long times and the quality of the finished product is assured only by the manual skill and by the experience of the operators, with the obvious drawbacks this entails.

Recently, machines with vibrating surface blade have been produced, which provide an internal combustion engine or electric motor mounted on a support frame, whereto is fastened a surfacing blade, in non rigid manner and through anti-vibration means. The surfacing blade is connected to an eccentric mass, in turn connected to the engine or motor by means of a transmission system. Alternatively, the-engine or motor can be fastened directly to the surfacing blade with

anti-vibration means.

On the support frame of said machines are rigidly fastened at least two handles to enable the operator to grip and handle the machine.

In addition to being particularly awkward in use, such machines have low efficiency and require a great consumption of energy in operation.

DISCLOSURE OF INVENTION The object of the present invention is to provide a machine with vibrating surfacing blade whose technical characteristics make it practical in use and highly efficient.

The present invention relates to a machine with vibrating surfacing blade, characterised in that it comprises a tubular support frame, a surfacing blade fastened in rigid fashion to said support frame, an engine fastened by anti-vibrating means to said support frame in proximity to said surfacing blade, a transmission system able to transmit motion from said engine to an eccentric mass connected to said surfacing blade, and at least one pair of grips fastened by anti- vibrating means to said support frame.

According to a preferred embodiment, the tubular

support frame comprises two curved end portions.

BRIEF DESCRIPTION OF THE DRAWINGS The example that follows serves illustrative and non limiting purposes, for a better understanding of the invention with the aid of the figures of the accompanying drawing, in which: Figure 1 is a perspective view of the vibrating surfacing blade according to a preferred embodiment of the present invention; - Figure 2 is a perspective view of the machine of Figure 1 with removed parts; - Figure 3 is a top view of a detail of the machine of Figure 1; and - Figure 4 is a top view of an additional detail of the machine of Figure 1.

BEST MODE FOR CARRYING OUT THE INVENTION In Figure 1, the reference number 1 globally designates a preferred embodiment of the machine with vibrating surfacing blade according to the present invention.

The machine 1 comprises a tubular support frame having a square section with variable dimensions. The frame 2 comprises a front end portion 2a and a rear end

portion 2b curved towards the same side. In particular, as clearly shown in Figure 2, the front end portion 2a has cone frustum shape.

The machine 1 comprises a junction element 3 fastened by means of four bolts 4 to the front end 2a of the frame 2, and a surfacing blade 5 fastened to the junction element 3 by means of two through bolts 6.

The machine 1 comprises a rear grip 7 fastened to the frame 2 in proximity to the rear portion 2b by means of four anti-vibration elements 8 shown in Figure 3.

The machine 1 comprises a front grip 9 fastened to the frame 2 by means of eight anti-vibration elements 8 shown in Figure 3. In particular, the front grip 9 comprises two handles 9a and 9b extending from opposite parts of the frame 2, in such a way as to enable both right handed and left handed persons to use the machine.

The machine 1 comprises an internal combustion engine 10 fastened to the frame 2 in proximity to the front portion 2a. In particular, the engine 10 is fastened on a support plate 10a, which in turn is fastened to the frame 2 by means of four anti-vibration element 8 shown in Figure 3.

The engine 10 is positioned at such a distance from

the surfacing blade 5 as to avoid being fouled by the concrete when the machine is in operation and being wet when the surfacing blade is washed.

As shown in Figure 3, the anti-vibration elements 8 are fastened on respective plates 8a, in turn fastened to the frame 2, and are positioned at the vertices of a quadrilateral in such a way as to assure their anti- vibration effect through the combination of the extension and compression action of the anti-vibration elements subdivided in pairs.

The machine 1 comprises an eccentric mass 11 housed in the junction element 3. The eccentric mass 11 is shown in Figure 4 and it has a disk shape with three circular sector openings 12. The eccentric mass 11 connected to a transmission system (known and not described in detail herein) comprising a flexible transmission shaft at whose end is mounted a rigid transmission segment whereon is keyed the eccentric mass itself.

An eccentric mass 11 thus designed represents different advantages, whereof the most important is the one pertaining to safety. The eccentric mass 11 of the present invention has no sharp edges and, therefore, if it disengaged from the transmission shaft, it would not

be able to puncture the junction element 3, but would remain within it without representing a hazard for the operator or for the persons who are in the working environment of the machine.

Other advantages of the eccentric mass 11 of the present invention pertain to its highly aerodynamic nature which results, with respect to commonly used eccentric masses, in less turbulence and, hence, a lower temperature and lower noise inside the junction element 3.

The flexible transmission shaft is partially housed in the front end 2a of the frame 2. The portion of the flexible transmission shaft outside the frame 2 is covered by a rubber protection 13 shown in Figure 1. The machine 1 comprises a guide element 14 fastened on the frame 2 and able to support the transmission shaft entering the frame 2. As shown in Figure 2, the guide element 14 is composed by a triangular plate 14a fastened on the frame 2 and by a tubular portion 14b extending from the plate 14a. In the tubular portion are positioned two bearings in which the transmission shaft is housed.

The guide element 14 allows to assure a straight conformation of the transmission shaft inside the frame

2.

The solution described above allows to avoid the need for assiduous maintenance of the transmission shaft.

The machine of the present invention has a high efficiency, since the vibration generated by the eccentric mass is transmitted to the whole frame 2, said frame being fastened to the surfacing blade 5 in rigid fashion. In this way, the vibration is transmitted amplified by the frame 2 to the surfacing blade 5. This vibration phenomenon allows the work of the engine to be contained, achieving energy savings.

The position of the engine 10 and of the grips 7 and 9 makes the machine particularly easy to handle, and the presence of the anti-vibration elements 8 assures that neither the engine nor the operator are affected by the vibration.

Moreover, an advantage of the machine of the present invention is that it can be used both moving forward and moving backward, which entails an enormous advantage in terms of working time.

As is readily apparent, the replacement of the internal combustion engine with an electric motor does not modify in any way the scope of the present invention.

Lastly, it has been demonstrated that, with respect to prior art techniques, laying concrete with the machine of the present invention in addition to requiring far less time, results in a finished product of considerably higher quality than the one obtained according to the prior art.