DESCRIPTION:

Technical field of the invention

The invention relates to a polishing and/or sanding head for a polishing and/or sanding machine for polishing and/or sanding a surface, comprising: at least two concentric discs provided with a front, which during operation faces the surface to be treated and on which a polishing or sanding sheet can be applied, and a rear, as well as a coupling for coupling a driven shaft of the polishing and/or sanding machine to one of the discs, and a transmission present between the disc coupled to the driven axle and/or the coupling and the other disc, which transmission is such that the two discs rotate in opposite directions about a common center during operation.

A disc is understood here to mean both round and ring-shaped discs. For applying the polishing or sanding sheets to the discs, the front of the discs and the back of the polishing or sanding sheets may be provided with interlocking hooks, as is the case with Velcro.

Background of the invention

A polishing and/or sanding head according to the preamble of claim 1 is known from CH 652 065 A. This known polishing and/or sanding head has two concentric discs provided with external and internal teeth, respectively, and a number of planet gears between the two teeth. These planetary gears are coupled via a transmission to a central shaft that can be coupled to a driven shaft of a machine. This construction causes the discs to rotate in opposite directions. During polishing or sanding, the polishing and/or sanding head is moved over the surface to be treated. It has been found that the treated surface is not completely smooth, but that there are areas on it that have an appearance different from other parts of the surface. Summary of the invention

An object of the invention is to provide a polishing and/or sanding head with which, when used in the same manner as the known polishing and/or sanding head, a more even polishing or sanding result is obtained than with the known polishing and/or sanding head. To this end, the polishing and/or sanding head according to the invention is characterized in that: the polishing and/or sanding head comprises three discs of which said two discs form part and of which the other disc is connected via a further transmission to the coupling or to one of the said two discs, said further transmission is such that during operation the other disc does not rotate but makes a circular movement about an imaginary axis.

Due to the presence of a third disc, which does not make a rotating but an oscillating movement (in two directions at right angles to each other), a smooth surface is obtained on which no areas with a deviating appearance are present.

Of the discs, a first disc is the innermost disc, the second disc is annularly surrounding the first disc, and the third disc is annular and surrounding the second disc. The polishing and/or sanding head can be arranged in such a way that one of these discs can make a circular movement and the other two discs rotate. Preferably, however, the first and second discs are rotatable in opposite directions about their center and the third disc is capable of circular motion. This circular motion means that the disk is oscillable in two perpendicular directions so that each point of this disk makes a circular motion about an imaginary axis, where the distance of each point of this disk to the imaginary axis about which this point moves is for all points equal.

A constructively favorable embodiment of the polishing and/or sanding head is characterized in that: a first gear is mounted on the rear side of the first disc, this first gear and the first disc being concentric, an annular second gear with an external toothing and an internal toothing is mounted on the back of the second disc, this second gear and the second disc being concentric, between the first gear and the second gear there is at least one planet gear meshing with the first gear and with the internal teeth of the second gear, and the second transmission comprises at least one third gear meshing with the external teeth of the second gear, said third gear is connected via an eccentric to the third disc.

Preferably, the eccentric has a shaft that is eccentric with respect to the third gear and is coupled to the third gear and to the third disc. The shaft is preferably mounted on the third gear or on the third disc and is rotatably provided in an opening in the third gear and in the third disk respectively.

The polishing and/or sanding head preferably has a frame wherein the at least one planetary gear and the at least one third gear are rotatably connected to the frame.

The invention also relates to a polishing and/or sanding machine comprising a drive provided with a driven shaft, as well as a polishing and/or sanding head according to the invention, of which the coupling is coupled to the driven shaft.

Brief description of the drawings

The invention will be explained in more detail below on the basis of an exemplary embodiment of the polishing and/or sanding head according to the invention shown in the drawings. Hereby:

Figure 1 shows the polishing and/or sanding head in top view;

Figure 2 shows the polishing and/or sanding head in bottom view;

Figure 3 shows the polishing and/or sanding head in side view;

Figure 4 shows the polishing and/or sanding head in section along line I- 1 in Figure 1 ;

Figure 5 shows the polishing and/or sanding head in section along line Illi in Figure 1 ; and

Figure 6 the polishing and/or sanding head in exploded view.

Detailed description of the drawings

Figures 1-3 show an embodiment of the polishing and/or sanding head according to the invention in top, bottom and side views, respectively. The polishing and/or sanding head 1 has a frame 3 and three discs 5, 7 and 9 movably coupled to the frame. Of these discs, a first disc 5 forms a round inner disc and a second disc 7 is annular and surrounds the first disc. These first and second discs 5 and 7 are concentric and rotatable in opposite directions about their common center 8. The third disc 9 is also annular and is provided around the second disc. This third disc 9 is not rotatable but can make a circular movement about an imaginary axis. The discs 5-9 are provided with a front side 5A-9A, which faces the surface to be treated during operation and on which a polishing or sanding sheet can be applied.

Gears are present at the rear 5B-9B of the discs 5-9. In Figures 4 and 5 the polishing and/or sanding head is shown in cross section along the lines I-I and II-II respectively indicated in Figure 1 and in Figure 6 the polishing and/or sanding head is shown in an exploded view. The transmissions formed by the gear wheels between the discs will be explained below on the basis of these figures. Mounted on the back side 5B of the first disc 5 is a first gear wheel 11 which is provided with external teeth 11 A. Mounted on the back side 7B of the second disc 7 is a second annular gear 13 which has an internal toothing 13 A and an external toothing 13B. Between the external gearing 11A and the internal gearing 13A are three planet gears 15 provided with external gearing 15 A.

The gears 11-15 form a first gear that is present between the first and second discs and causes the discs to rotate in opposite directions. The planet gears 15 are mounted in frame 3 by means of bearing blocks 16. Furthermore, three third gears 17 provided with external gears 17B are mounted in frame 3 by means of bearing blocks 18. These third gears 17 form a second transmission with the second gear 13. Pins 19 are mounted on these third gears 17, which are located away from the center of the gears 17 and form an eccentric. These pins are rotatably present in openings 20 in the third disc 9 and ensure that this third disc 9 makes an eccentric movement whereby his third disc 9 does not rotate about its center.

The first gear wheel 11 is coupled to a coupling piece 21 with which this gear wheel can be coupled to a driven shaft of the polishing and/or sanding machine. Also attached to the frame is a handle 23 with which the polishing and/or sanding head can be moved over the surface to be treated.

Although the invention has been elucidated in the foregoing with reference to the drawings, it should be noted that the invention is by no means limited to the embodiment shown in the drawings. The invention also extends to all embodiments deviating from the embodiment shown in the drawings within the scope defined by the claims.