Such a device is used to smooth the surface of, in particular, poured concrete floors, for which purpose the polishing blades of the rotor are rotated at a determined rotation speed, which polishing blade can have a determined pre-adjustable angle relative to the rotation axis. Known devices of this type have the drawback that the adjustment of the angle of each polishing blade relative to the rotor shaft must be embodied in quite complicated manner. This requires much time, and therefore loss of production.

The invention has for its object to obviate the above stated drawbacks and provides for this purpose a device which is distinguished in that an annular support member is arranged concentrically round the drive shaft and is pivotally connected to each blade at a distance from the shaft such that a rotation of the ring brings about an equal and simultaneous tilting of each blade.

Owing to the common support ring of the polishing blades, not only is a simultaneous angular adjustment of the polishing blades ensured, but the ring also provides some support of the blades at a distance relative to the rotation axis. Excessive vibration or other deviations of the polishing blades are hereby prevented, whereby a better final levelling result is realized.

In order to adapt the machine in simple manner to the diverse finishing processes depending on the type of floor, it is recommended to mount the polishing blades exchangeably on a rotor arm. This exchange capability can take place by means of clamping means such that the

blade can be released and a new blade can be mounted using a simple screwed connection.

In this embodiment it is recommended to arrange each rotor arm with one end for rotation in a bush of a carrier connected to the shaft, which arm is provided with an adjusting plate with adjustable stop.

The desired angular adjustment of the blades is achieved in simple manner owing to this stop.

In a preferred embodiment the support ring is also provided with a shock absorber in a pivot with the rotor arm. Possible undesired vibrations can hereby be easily damped, which contributes towards a good final result.

Above mentioned and other features of the invention will be elucidated in the figure description below of an embodiment. In the drawing: figure 1 shows a perspective elevated view of the device according to the invention; figure 2 shows a top view of the rotor with polishing blades as applied in the device of figure 1; figure 3 shows a perspective top view of a part of the rotor provided with rotor arms and polishing blades, in exploded assembly.

The device shown in figure 1 comprises a frame 1 with a motor 2 placed thereon, wherein the device is also provided with a safety cage around the motor which projects over the operating range of the group of polishing blades placed thereunder, whereby the user-is not struck by the rapidly rotating polishing blades.

By means of a handle with control means the device can be moved back and forth by the user over a recently poured floor in a predetermined pattern, this not being further elucidated here since it is deemed known by the skilled person.

Rotor 5 is shown in top view in figure 2, and consists of a central hub part or rotor holder 5 which is embodied with a number of bush-shaped protrusions, the number of which corresponds with the number of polishing blades used.

The holder can be mounted in known manner on the vertically standing motor shaft such that a torque can be transmitted onto the rotor from the motor.

Each polishing blade is provided with a rotor arm 6 on which the polishing blade 7 can be mounted exchangeably, this being further elucidated hereinbelow.

Arranged concentrically round the central shaft of carrier 5 is a support ring 8 which also serves as support ring for arms 6 and therefore polishing blades 7, since the diameter of ring 8 is such that the polishing arms are supported about halfway along their length.

Referring to figure 3, in which the same reference numerals are used for the same components, each rotor arm 6 has a pin-shaped end part 9 which can be placed into the bush-like protrusion 10 of holder 5. A rotating movement of rotor arm 6 around its central axis is hereby possible. End part 9 is provided with a peripheral groove 11 in which a pin, which can be inserted into a pin hole 12 of protrusion 10, is axially placed so that rotor arm 6 is received rotatably but not displaceably in the hole of protrusion 10.

The rotor arm is provided with a block 13 which is attached fixedly to the underside of rotor arm 6 by means of bolts or the like, as well as a clamping part 14 which can likewise be fixed against the end face of rotor arm 6 by means of bolt 15, such that a ridge 16 of polishing blade 7 can be received and fixed between clamping means 13,14. In this manner the polishing blade 7 can be released easily from the rotor arm by loosening bolt 15, and a new blade can be fixed in simple manner by tightening bolt 15.

On the side of rotor arm 6 remote from the polishing blade is arranged a block 17 provided with a hole 18 in which a rubber bush 19 can be placed, in which bush a bolt 20 can be placed into a threaded hole of ring 8. Rubber bush 19 herein serves as vibration or shock damper.

Fixed by means of bolts 22 on the end of rotor arm 6 directed toward holder 5 is an adjusting plate 21

which is provided with an adjustable stop screw 23 which can be placed in a hole 24 of plate 21. This bolt supports on a disc 25 of holder 5, this such that by rotating the rotor arm 6 the end part of bolt 23 moves against disc 25, and therefore adjusts a determined angle of polishing blade 7 relative to the rotation axis.

The simultaneous adjustment of all polishing blades with their rotor arms 6, each of which is arranged in a protrusion of rotor 5, enables simultaneous adjustment of all polishing blades at the same angle relative to the rotation axis.

The invention is not limited to the above described embodiment. Polishing blade 7 can thus be arranged rotatably on a fixed rotor arm 6, wherein ring 8 is then coupled directly to polishing blades 7.

The mounting of polishing blade 7 on rotor arm 6 by means of the ridge 16 and clamping means 13,14 can also be embodied in any suitable manner, for instance by means of direct arranged screw bolts.

It is also possible for two rotors to be applied per device instead of the single rotor machine according to figure 1.