Technical field

This invention generally lies within the field of apparatuses for treating surfaces; in particular, the invention relates to a polishing and/or sanding head for treating surfaces.

Prior art

Known apparatuses suitable for polishing or sanding surfaces, for example car bodies, typically comprise a power tool which may be operated manually by an operator and is provided with a rotating shaft that has, on its tip, a discoid element made of a more or less abrasive material suitable for treating the surface when rotated by the tool. The rotating element generally comprises or supports a cloth which, when the apparatus is operated by the operator, distributes a polishing or abrasive paste onto the surface to be treated.

Examples of apparatuses of this kind are known, for example, from CN 103 862 351 A, EP 1 586416 A2, and US 6007 412 A.

However, one problem of these apparatuses is that they are not able to homogenously treat the surface, for example by uniformly spreading the polishing paste, and therefore the final quality of the treated surface may not be satisfactory on account of having aesthetically different regions (presence of marks, opaqueness, etc.).

Understandably, this defect limits the usability of the apparatus and the quality of the treatment.

Summary of the invention

The object of this invention is to overcome the aforementioned problems.

In order to achieve this, a processing head is provided which is designed to allow the simultaneous use of two abrasive or polished surfaces, made of identical or different materials, which are simultaneously operated (rotated) in opposing directions.

The aim in operational terms is to obtain more homogenous processing that has a higher finishing level by comparison with using conventional systems for these operations, which only have one type of material that may rotate in only one direction.

The device is particularly suitable for treating painted surfaces of cars, but its use may be extended to any context in which a surface is prepared by means of sanding and/or a surface is finished by means of polishing.

The head is advantageously designed to be connected to a rotary power tool, for example those normally used in the bodywork field. Another possible field of use may be, for example, that of polishing floors that are made of wood or other materials (marble, other stones, or ceramics).

The concurrent rotation of the treatment surfaces, supported by the head, is achieved by means of a planetary speed reducer which comprises a central “sun” gear, one or more “planet” gears and an internally toothed gear known as a “ring gear”. This reducer is characterized by the fact that, in a head according to this invention, the system of “planets” is kept stationary and constrained, instead of keeping the “ring gear” stationary.

The rotary motion is applied to a shaft which is integrally connected to the sun gear. The one or more planets are kept in a fixed position with respect to the axis of the head and are only free to rotate about their own axis. The planets engage with a toothed gear comprising internal toothing (the ring gear), which toothed gear is free to rotate on account of the motion transmitted thereto by these planets. In a head according to this invention, both the sun gear and the ring gear are rotatable with respect to the planet holder.

If a cylindrical surface is mounted on the sun gear, this surface will rotate in the same direction of the source of the motion; however, if a planar circular annulus is mounted on the external ring gear, this ring will rotate in an opposite direction to the surface mounted on the sun gear. The two surfaces, i.e. the cylindrical surface and annular surface, advantageously lie with the exposed surface on the same plane; the processing means (abrasive surface or polishing surface) is applied to these exposed surfaces.

The aforesaid and other aims and advantages are achieved, according to one aspect of the invention, by a polishing and/or sanding head for treating surfaces that has the features defined in claim 1. Preferred embodiments of the invention are defined in the dependent claims.

Brief description of the drawings

The functional and structural features of some preferred embodiments of a polishing and/or sanding head for treating surfaces according to the invention will now be described. Reference is made to the accompanying drawings, in which:

- Fig. 1 is a perspective view, in diametral cross section, of a polishing and/or sanding head for treating surfaces, according to one embodiment of this invention;

- Fig. 2 is a perspective view, from below, of the head in Fig. 1, with the treatment surfaces removed in order to show the planetary transmission inside the head; and

- Fig. 3 is the perspective view, from below, of the head in Fig. 2, with the treatment surfaces reinstated.

Detailed description

Before describing in detail a plurality of embodiments of the invention, it should be clarified that the invention is not limited in its application to the design details and configuration of the components presented in the following description or illustrated in the drawings. The invention is able to assume other embodiments and to be implemented or constructed in practice in different ways. It should also be understood that the phraseology and terminology have a descriptive purpose and should not be construed as limiting.

With reference, by way of example, to Fig. 1, a polishing and/or sanding head 9 comprises a primary disc 10 which is axially hollow, and a rotating shaft 12 which is received in the internal cavity of the primary disc 10 and rotatably supported by the latter.

The rotating shaft 12 is designed in such a way as to receive a rotary motion about an axis coincident to the axis of the primary disc 10 (axis x) by means of a power take-off external to the head 9.

There is also a body 14 present, which body is radially external and coaxial with respect to the rotating shaft 12, said body 14 being rotatably supported by said primary disc 10.

The head 9 also comprises a planetary gear transmission which is adapted to transmit the rotational motion of the rotating shaft 12 to the body 14, the transmission comprising: a sun gear 18 which is integral in rotation with the rotating shaft 12 and has an external toothing facing the body 14; a ring gear 20 which is integral in rotation with the body 14 and has an internal toothing facing the axis x of the primary disc 10; and at least one planet gear 22 which is supported by the primary disc 10 so as to be rotatable about a secondary axis y which is parallel and not coincident with the axis x of the primary disc 10.

The planet gear 22 is placed in an intermediate position between the sun gear 18 and the ring gear 20 in such a way as to engage both and transmit a rotary motion from the former to the latter.

The head 9 also comprises a first support for a treatment means 24 which is integral in rotation with the rotating shaft 12 and has an exposed surface adapted to form or support a means suitable for polishing or sanding a surface to be treated, and a second support for a treatment means 26 which is integral in rotation with the body 14 and has an exposed surface adapted to form or support a means suitable for polishing or sanding said surface to be treated. These first and second supports for a treatment means 24, 26 are designed, respectively, as a circular element and an annular element that are concentric to each other, and the second support for a treatment means 26 counter-rotates around the outside of the first support for a treatment means 24 (i.e. is able to rotate in an opposite direction with respect to the direction of rotation of the latter, which is set by the rotating shaft 12). The first and second supports for treatment means 24, 26 are preferably designed to form or support a means suitable for polishing and/or sanding a surface to be treated that is made of painted metal (for example a car body) or wood or stone or marble or ceramic.

The exposed surface of the first and/or the second support for a treatment means 24, 26 is advantageously formed at least partially from a felt cloth of a kind known per se or is designed to support a treatment means formed at least partially from a felt cloth.

According to a preferred embodiment, the exposed surface of the first and/or the second support for a treatment means 24, 26 is formed at least partially from an expanded polymer cloth or is designed to support a treatment means formed at least partially from an expanded polymer cloth.

The exposed surfaces of said first and second supports for a treatment means 24, 26 are preferably mutually coplanar.

According to one embodiment, the rotating shaft 12 comprises a flange rotatably supported by the primary disc 10 by means of a rolling bearing.

The at least one planet gear 22 is preferably supported by the primary disc 10 so as to be rotatable about a relevant secondary axis y by means of a pin 23 fixed to said primary disc 10, such that the secondary axis y is fixed in rotation with respect to the axis x of the primary disc 10.

According to one embodiment, the head 9 comprises three planet gears 22 circumferentially equidistant along the primary disc 10.

The primary disc 10 may advantageously be designed to couple to a portable apparatus equipped with a power take-off that may be coupled to the rotating shaft 12.

For example, the primary disc 10 may be designed to couple to a traditional handheld power tool for polishing and/or sanding car bodies. Various aspects and embodiments of a polishing and/or sanding head according to the invention have been described. It is understood that each embodiment may be combined with any other embodiment. Moreover, the invention is not limited to the embodiments described, but may be varied within the scope defined by the appended claims.