IMPROVED SUCTION SANDING TOOL

DESCRIPTION

Technical field of the invention

The present invention concerns the field of sanding tools in particular but not exclusively intended for boat construction. More specifically, it regards a new improved suction sanding tool having an elongated structure and preferably flexible.

Background of the invention

Various types of sanding tools are known, comprising amongst other things motorised tools in which the abrasive element is actuated with linear, orbital or roto- orbital motion depending on the case. A different family of sanding tools is of the manual type, i.e. tools in which the sanding motion is entirely dependent on the manual actuation of the entire tool with respect to the surface to be sanded. For some applications, in particular in shipbuilding or boat construciton, tools of this kind take up an elongated bar-type configuration, which can indeed be advantageous in the case of some processing (smoothing and removal of plaster or other excess materials) on large surfaces like for example the walls of hulls. There are also known tools, also only manual, which provide for a suction system for the suction of debris and sanding dust. In this case they are compact devices, of small dimensions, the use of which for processing requirements like in the nautical field is greatly limited.

Among known sanding tools there is also that described in PCT publication WO2014/072959, according to which a box-like body having an elongated shape with respect to a longitudinal axis defines an inner chamber, and a working wall parallel to the longitudinal axis bearing a plurality of suction holes. The body also comprises means for the releasable connection of a sheet of abrasive material, in turn perforated, and a pneumatic system for exerting or transmitting a depression inside the chamber. The pneumatic system comprises at least two tubular manifolds arranged in series along the longitudinal axis, pneumatically communicating with the chamber and mechanically connected to the body on the opposite side with respect to the working wall. The at least two manifolds are regularly spaced so as to affect substantially the entire longitudinal extension of the body and comprise a supply manifold provided with connection means to an outer depression source, and at least one blind tail manifold. The at least two manifolds are pneumatically and mechanically connected to each other by at least one respective duct segment.

Summary of the invention

The present invention now offers a new manual sanding device that, in the context of a suction solution that provides for a body having an elongated bar shape, manages to marry full effectiveness, in terms of power and uniformity of suction over the entire working surface, with a remarkable ease of handling and with a substantial constructive simplification.

According to the invention, this and other secondary objects are accomplished by an improved suction sanding tool the essential characteristics of which are defined by the first of the attached claims.

Brief description of the drawings

The characteristics and advantages of the improved suction sanding tool according to the present invention will become apparent from the following description of an embodiment thereof, made as a non-limiting example with reference to the attached drawings, in which:

figure 1 is an axonometric view of a tool according to the invention;

figure 2 is an exploded axonometric view of the device of figure 1 ; and;

- figure 3 is a longitudinal section view of the tool, according to the section plane Ill-Ill of figure 1.

Detailed description of the invention

With reference to the above figures, the tool according to the invention comprises a box-like body 1 having an elongated shape according to a longitudinal axis X. The body comprises at least one flat working wall 1 1 a parallel to the axis X and that externally defines the sanding face or surface, i.e. the one intended, once lined with a perforated sheet of abrasive material 2, to exert the sanding action by coming into contact with the surface to be sanded. The sheet 2 is connected to the flat wall 1 1 a through removable connection means such as perforated adhesive straps with Velcro ^® system, as made clearer hereafter. The sheet 2 and part of the connection means, not represented in the figures, represent disposable components obtainabl from what is available on the market (sandpapers of different characteristics depending on requirements).

The box-like body 1 preferably, like in this case, has a structure that is flexible with respect to a transversal bending axis, i.e. parallel to the wall 1 1 a in the semi- space defined by the wall itself and excluding the body 1 , as well as perpendicular to the axis X. Such a characteristic can be advantageously achieved according to this embodiment, with a base 1 1 and a cover 12 represented simply by flat walls (working and cover walls, respectively), made from compact polycarbonate or other relatively rigid material that seconds a certain bending, like for example Lexan ^® , carbon, composite materials or a combination of such materials; these two walls are joined, as well as by head pieces 13 at the longitudinal ends, by side pieces 16 developing in the direction X and made from a flexible and elastic material such as a synthetic rubber (for example EPDM foamed rubber mixed with chloroprene).

As just mentioned, at the two longitudinal ends the body 1 provides for respective head pieces 13 that complete the surface development thereof, so that inside it a closed chamber 14 is formed. The chamber 14 is intended to receive a pneumatic depression and opens onto the outside through a plurality of suction holes 1 1 a that open widely and regularly on the entire working wall 1 1 . Correspondingly to the holes 1 1 a the abrasive sheet 2 will bear an identical pattern or array of holes 21 to allow the passage of the suction flow. The holes 21 , 1 1 a respectively on the paper 2 and on the wall 1 1 will be in organised arrays so as to affect, as mentioned in a diffuse and regular manner, the entire working wall, comprising narrow holes (diameter less than 10 mm) spaced apart by a few tens of mm (minimum and maximum centre-to-centre distance between one hole and the closest hole, respectively, of about 20 mm and about 80 mm).

An external sealing wrap then has the shape of a covering case 3 made of synthetic textile material. Such a case ensures the pneumatic seal and makes available or incorporates the connection means (as stated such as Velcro ^® means) for the perforated sheet of abrasive material. The case will in turn bear holes 31 suitable for corresponding with the suction holes of the working wall and can in turn use Velcro ^® systems to remain stably fixed and enveloped around the body 1. Possibly, the entire case can be made from Velcro ^® fabric, suitably shaped and also equipped with an adhesive inner face for a firm connection to the wall 1 1 . A further mechanical fastening can be provided, for even greater safety, between the upper portion of the cover and the wall 12. The side pieces 16 can possibly have, like in the example, recesses 16a to avoid blocking the more peripheral suction holes 1 1 a.

The depression in the chamber 14 is obtained according to the invention preferably by means of a single hole 12a formed in the cover wall 12, near to a longitudinal end, i.e. to a head piece 13. For the rest, the cover wall is continuous. Again according to an aspect of the invention, the inner chamber 14 is divided by a distribution diaphragm 15 that in turn develops parallel to the working wall 1 1 and to the cover wall (if it is also flat like in this example), spaced apart substantially equally among these two walls. The diaphragm thus defines an upper compartment 14a and a lower compartment 14b of the chamber 14.

Such two compartments are placed in communication by a plurality of holes 15a formed in the diaphragm 15 preferably (but not necessarily) aligned on the middle longitudinal axis of the body. The holes 15a are also preferably equally spaced and in a number that essentially depends on the length of the body itself. In the variant embodiment here illustrated there are for example five holes. The criterion for the selection of the number of holes is that of an even distribution of the depression over the entire development of the chamber 14, and more specifically of its lower compartment 14b, considering that for this purpose the distance (pitch) between one hole and another, assuming a suction power selected in the order of 1200-1400 W, must not in any case exceed 500 mm. The diameter of the holes 15a will preferably be comprised between 15 mm and 25 mm, and there will be at least two holes, in the context of a body having a length in any case not less than 40 cm and a width comprised between 7 cm and 15 cm.

The diaphragm 15 is also made from the same rigid but relatively flexible material of the two working and cover walls, and is supported by means of an appropriate interlocking with the head pieces 13 and the side pieces 16, which can also be made in two parts (like in the example indicated as 13 and 13', 16 and 16' in figure 2 and figure 3) and using (which can apply to all the other assembly elements of the body) suitable gluing means.

Therefore, it is through the head hole 12a, equipped with a cylindrical manifold 17 for the attachment of an external depression source, that the suction flow reaches the tool, and is then transmitted from it firstly to the upper compartment 14a, becoming uniform in it, and then through the holes 15a on the diaphragm 15 to the lower compartment 14b. Thanks to such a configuration and in particular to the distributor role carried out by the diaphragm 15, the suction reaches and affects in a surprisingly strong and homogeneous manner the entire longitudinal development of the chamber 14, being effective through the holes 1 1 a on the entire working wall or base 1 1 up to the area furthest from the single entry hole and also in the case in which the body has a substantial longitudinal extension (up to three metres and more). Such a result derives in particular from the suitably sized and localised configuration of the distribution holes on the diaphragm in relation, on the other hand, to a densely and extensively distributed configuration of the suction holes on the working wall.

There is thus the possibility of making a tool of great length while still maintaining an effective suction capability, in order to work large surfaces, also following the curvatures thereof, possibly with precision and without undulations, thanks to the preferred variant with flexible body 1 , without giving up the advantages of the suction that is of substantial importance to protect the health of workers, decrease the consumption of sandpaper and preserve the quality of the sanding quality (the suction ensures that residue does not form between the paper and the surface to be worked, with the consequent risk of scratching or in any case alteration of the abrasive quality).

The fact that most of the tool has no projecting parts (with the exception of the manifold 17 that in any case can be made so as to limit or even nullify the protrusion, for example in a configuration aligned with the longitudinal direction/axis) and that therefore the cover is smooth, can allow easy direct handling by skilled workers, or the positioning of removable handles, to nevertheless be arranged in the position freely chosen as most favourable according to requirements. The position of a handle can also be selected so as to create a greater sanding pressure at a specific point, where this is advantageous. Such removable handles can for example use, for the connection to the body 1 , Velcro ^® systems or mechanical systems with elastic snap-type arms or similar. In this way the type and number of handles can also be changed according to requirements.

This results in a substantial advantage with respect to systems with rigid and non-removable handles that perhaps can even be a hindrance depending on the specific nature of a particular processing. Obviously, the ease of handling is contributed to, as well as by the possibility of finely adjusting, with continuity based on the sensitivity of the worker and the needs set by the processing, the degree of curvature of the body, by the fact that the tool has a single attachment point and in general a light structure despite the length. The solution achieved thanks to the invention is in general productively simple and extremely cost-effective, also allowing a substantial curvature of the body, to determine a concave and convex working surface, which is continuous and without limitations set by localised stiff areas (for example due to the presence of outer manifolds distributed along the body), with an elastic return to the straight configuration without permanent deformations.

As stated, the flexibility of the body 1 can represent an advantageous characteristic, but the main use of the invention can be obtained even with a rigid body 1 in the straight configuration. In this case the side pieces can for example be made from aluminium and connected to the various walls with riveting systems or similar.

Going back to the structural configuration of the tool, the supply hole arranged at the head, i.e. at or near to a longitudinal end of the body (distance of no more than 20 mm from the end) it is advantageous for the handling of the tool in the majority of situations, and for greater freedom in the arrangement of the handles as indicated above. However, theoretically, the advantages of the invention can be obtained at least in part also with a manifold not at the head, for example in central position, and even with a number of manifolds greater than one. In this case, although only partially, some advantages of the invention, deriving from the particular pneumatic distribution created through an inner diaphragm, can still be obtained.

The head manifold 17 can have a flow regulating passage, not represented, the degree of opening/closing of which can be regulated simply through manual blocking or with a telescopic system, resulting in a decrease/increase in suction power. A window on the cover wall 12, closed by a removable cap, also in this case not represented, can finally be provided for to promote the removal of possible residual dust that has accumulated inside the chamber 14.

The present invention has been described with reference to preferred embodiments thereof. It should be understood that there can be other embodiments within the scope of protection as defined by the claims here attached. In particular the constructive solutions for making the body 1 can be the object of other variants (with it also being able to comprise transversal inner dividing walls, i.e. perpendicular to the longitudinal axis X, to physically divide the chamber 14 into many mutually distinct suction spaces).