Double suction chamber plate

A plate for machining surfaces is provided, comprising a body with bores and channels for aspirating dust, on the top of which a deflector is hooked. Said deflector includes at least one vertical curved wall adapted to define a double suction chamber consisting of a peripheral chamber and of a central chamber.

This application claims the priority of Italian no. MI2011A001434 filed Jul. 29, 2011, hereby incorporated by reference.

The present invention relates to a double suction chamber plate.

European Patent application EP-1514644-A1 by the Applicant describes a circular shaped plate for machining surfaces, comprising a flexible, perforated body made of polyurethane foam, in which a rigid support is sunk. Said plate is further provided with bores and cavities, and is placed in rotational or roto-orbital motion, in relation to the frame of the portable tool that supports it, by a mechanism which forms part of the portable tool itself, and is connected to a suitably shaped central pin, fastened to said rigid support. A thin layer of perforated Velcro covers the lower surface of the plate, allowing the adhesion of a sheet of abrasive material intended to cooperate with the surface to be machined.

The external edge of said rigid support is shaped so that a deflector on which a cap rests can be snap-fitted, the cap equipping the portable tool, in order to contain and convey the dust drawn therein through said bores and cavities towards a suction tube.

During the step of machining, the plate moves with rotational or roto-orbital motion relative to the frame of the tool to which it is linked, and the dust produced by the cooperation of the abrasive sheet with the surface to be machined is removed by means of a suction system. The dust particles pass through said bores and cavities and reach the upper part of the plate to then continue within the suction tube conveyed firstly by the deflector and then by the suction cap. The suction flow forces the dust to go towards the center of the plate, from where it can ascend towards the suction tube, possible side leakages being stopped by the presence of the junction cap and by the direction of the suction flow.

The use of a deflector constructionally allows to perforate the body of the plate at will, and accordingly to create any bore layout (in terms of diameter, number and arrangement of the bores themselves) specifically structured to limit the loss of machining dust into the surrounding environment and to increase the aspirated air flow (or other types of customizations even for commercial purposes). Furthermore, the aforesaid deflector “guides” the dust towards the suction tube without overstressing the junction cap which could be a precarious seal, and provides the cap itself with a better, smoother contact and sliding surface which improves tightness and reduces wear.

The plate with deflector described in said European patent application has the drawback of having a low suction power in the most peripheral zone, spaced apart from the central suction zone. Therefore, the dust particles which cross the most peripheral bores of the plate may be deposited over the plate body or under the deflector in the most peripheral part thereof, where the suction power is much lower and not sufficient to remove them.

It is the object of the present invention to provide a plate with deflector which improves the suction of dust at the peripheral zones of the plate, identified at the suction bores located at a greater distance from the center of the plate itself.

In accordance with the invention, such an object is achieved by a plate for machining surfaces that comprises a body with bores and channels for dust suction on which a deflector is hooked on the top, characterized in that said deflector comprises at least one curved vertical wall adapted to define a double suction chamber formed by a central chamber and by a peripheral chamber.

A portable machine tool for machining surfaces includes a circular shaped plate1comprising a body2consisting of a rigid support10made of thermoplastic material, preferably nylon, and a flexible perforated body11, preferably made of polyurethane foam, wherein said rigid support10is sunk. Said plate1is also provided with bores3and cavities4, and is placed in rotational or roto-orbital motion, relative to the frame of the portable tool that supports it, by a mechanism (not shown in the figures) that forms part of a portable tool and is connected to a suitably shaped central pin5, fastened to the rigid support10.

A thin layer of perforated Velcro6(or other suitable material) covers the lower surface of the plate1, allowing the adhesion of a sheet of abrasive material intended to cooperate with the surface to be machined.

A circular deflector7, on which a cap9(FIG. 2) rests, is snap-fitted over the body2of the plate1(FIGS. 1-4), the cap equipping the portable tool in order to contain and convey the dust drawn therein through the bores3and the cavities4towards a suction tube. Further suction bores31are provided, which are referred to as “peripheral” bores because they are arranged at a greater distance from the center of the plate1.

The deflector7, clearly seen inFIGS. 3 and 4, is hooked by snapping onto the rigid support10by means of a curved vertical wall71(possibly split into several sectors), which couples to an inner curved edge13of the rigid support10. The fastening occurs by coupling the end teeth80of the wall71and81of the edge13of the rigid support10.

The walls71and the edge13have the same curvature radius as the circular plate1.

The deflector7further includes a flat outer portion76with outer edge74, and a flat inner portion79with inner edge73.

Ribs78which end with flat portions71laying on a radial plane which reach the inner edge73of the deflector7radially depart from the vertical wall71. The outer edge74of the deflector7is adjacent to a curved outer edge15of the body2. Said flat portions72allow to more effectively address the dust towards the center of the plate1, thus facilitating its suction.

There is provided an inner annular rib75which connects said flat portions72increasing its rigidity.

The coupling between the deflector7and support10determines the formation of a double suction chamber consisting of a peripheral chamber20, into which the dust flows from the peripheral bores31of the plate1, and of a central chamber21, into which the dust flows from the bores3.

The peripheral suction chamber20is defined, as clearly shown inFIG. 2, by approaching the wall71and the flat outer portion76of deflector7to the plane13and the outer edge15of the rigid support10.

The central suction chamber21is open inwards and delimited by the wall71and by the inner flat portion79of deflector7, and by the support10. The dust from the bores3and from the peripheral chamber20is conveyed into said chamber21by means of openings22obtained in the wall71(FIGS. 3 and 4).

FIGS. 5-8show a second embodiment of plate1(the same numerals being used for similar parts), where a deflector700is hooked to the rigid support10of the plate by means of a connection (a screw connection100, by way of non-limiting example) at a central part101of the support10near pin5.FIGS. 5-8describe, by way of non-limiting example, a fastening system of the deflector characterized by a nut screw102of a central annular mouth103of the deflector700which is screwed onto a screw104obtained onto an annular edge105of the central part101of the rigid support10.

The deflector700shown inFIGS. 5-8is completely similar to the deflector7ofFIGS. 1-4, except for the means and connection points with support10, which are no longer fitted onto the outer diameter but onto an inner diameter of the same instead. Therefore, the curved vertical wall71has no coupling teeth80, exactly like the curved inner edge13is not provided with coupling teeth81. In the embodiment shown inFIGS. 5-8, the peripheral suction chamber20is defined by approaching the wall71and the flat outer portion76of the deflector700to the surface13and the outer edge15of the rigid support10.

The deflector700completely covers the suction bores3,31and has cracks701for the dust to pass from the suction chambers20and21to the space inside the cap9.

The central suction chamber21is closed inwards and delimited by vertical curved wall71, inner flat portion79of deflector700, support10and central annular mouth103. The dust coming from the bores3,31is conveyed into said suction chambers20and21, which communicate through the openings22of wall71.

The generated dust is advantageously aspirated more efficiently in the most peripheral zone of the plate through the peripheral bores31, then enters the peripheral chamber20, through the openings22and enters the central chamber21to then be conveyed into the cap9and then towards the suction tube. Thereby, the lower surface of the plate effectively contributes, in addition to machining, also to aspirating the generated dust.

The curved walls71of the deflectors7,700of the two described embodiments regulate the vacuum difference between the chambers20and21by means of the openings22. Therefore, an increase in the particle speed in the more peripheral zone under the deflectors7,700, i.e. in the peripheral chambers20, is found. Under normal conditions, such an increase in speed determines an increase in the depression with respect to the ambient values of the machined surface, and thus an increase in the suction power at the outer zone of the plate. The peripheral chambers20substantially accelerate the motion of the dust particles by aspirating them from the peripheral bores31. The dust particles advantageously reach the central chambers21being accelerated through the spaces22.

The combined effect of peripheral bores31and peripheral suction chambers20determines the possibility, by means of a different distribution of the bores, to obtain different configurations, privileging suction where it is most convenient according to the type of machining and the aspirated dust flow.