AN ELONGATED AIR SANDING TOOL

DESCRIPTION

Technical field of the invention

The present invention refers to the field of smoothing or sanding tools in particular but not exclusively intended for shipyards. More specifically, its object is a new suction sanding tool with an elongated and preferably flexible structure.

Background of the invention

Various types of sanding tools are known, including motorised tools in which the abrasive element is actuated with a linear, orbital or rotary-orbital motion according to the cases. A different family of smoothing tools is of the manual type, i.e., tools in which the smoothing motion entirely relies upon the manual actuation of the entire tool with respect to the surface to be sanded. For some applications, in particular in shipyards, tools of this kind take up the configuration of an elongated bar, which can indeed be advantageous in the case of some processing (smoothing and removal of putty or other materials in excess) on large surfaces such as for example the walls of the hulls. There are also tools, even only manual, which comprise a suction system for sucking debris and sanding dusts. These are compact devices, with small size, the use of which for machining requirements such as nautical uses is highly limiting.

Summary of the invention

The present invention offers a new device for manual sanding that, through a novel configuration, combines in a particularly effective and useful manner the prerogatives of the suction system with those of manual tools with an elongated bar- shape, achieving considerable advantages in particular in smoothing large surfaces such as the sides of vessels in nautical shipyards.

According to the invention, this and other secondary objects are achieved with an air sanding tool with an elongated structure the essential characteristics of which are defined by the first of the attached claims.

Brief description of the drawings

Characteristics and advantages of the sanding tool according to the invention shall become clearer from the following description of an embodiment thereof, given as an example and not for limiting purposes with reference to the attached drawings, in which:

-figure 1 is an axonometric exploded view of a tool according to the invention in a first embodiment;

-figure 2 is a schematic representation of the tool of figure 1 in a side view, in a configuration of use in which it is flexed for smoothing a curved surface;

-figure 3 is a side view of a tool that is analogous to that of the previous figures but in a different variant embodiment, the tool being represented in a straight configuration and with a disposable sheet of sanding material (and relative material for securing it to the tool) that is detached from the actual tool;

-figure 4 is a view from below, i.e. from the side of the sanding surface, of the tool of figure 3;

-figure 5 is an enlarged view of figure 4 showing more in detail a preferred distribution of holes on the abrasive paper intended for being used in the tool according to the invention;

-figures 6 and 7 are axonometric views of the tool according to the invention in a different embodiment, respectively in the configuration of use and a in a broken view (figure 7) that makes it possible to see inside the structure.

Detailed description of the invention

With reference to figures 1 to 5, the tool according to the invention comprises a box-shaped body 1 with an elongated shape according to a longitudinal axis X. The body comprises at least one flat working wall 11a that is parallel to the axis X and that externally defines the sanding face or surface, i.e. the one that is intended, once it has been covered with a sheet of perforated abrasive material 2, to exert the smoothing action coming into contact with the surface to be sanded. The sheet 2 is connected to the flat wall 11a through reversible connection means such as perforated adhesive strips with a Velcro ^® system 3. The sheet 2 and part of the connection means 3, not represented in figure 1 , represent disposable components that can be obtained from what is available on the market (abrasive paper with different characteristics according to the requirements). As shall become clearer hereafter, the elongated band shape, and the relative dimensions, of the sheet 2 constitute characteristics that are special and are studied in connection with the present invention.

The box-shaped body 1 , made from aluminium, but possibly also from sheet metal or in any case other materials that are suitable (see what mentioned later as far as a different embodiment is concerned), preferably has, like in this case, a flexible structure with respect to a transversal bending axis, i.e. parallel to the wall 11a in the semi-space defined by the wall itself and excluding the body 1 , as well as perpendicular to the axis X. Such a prerogative can be achieved according to this embodiment, as visible in particular from figure 1 , by assembling a base 11 , which in addition to the wall 11a includes two side pieces 11 b that project opposite one another from the long sides of the flat wall 11a. The side pieces 11 b have cuts 11c that are regularly spaced, perpendicular to the flat wall 11a, indeed suitable for opening so as to ensure the aforementioned bending.

The aforementioned bending is assisted by a cover 12 that closes the base 11 at the top and determines the box-shaped structure of the body 1. The cover 12 is symmetrical and matching with respect to the base 11 and comprises a flat top wall 12a that is parallel and opposite with respect to the working wall 11a and two side pieces 12b that are inserted over one another inside with respect to the side pieces 11b of the base 11. The side pieces 12b, again according to this constructive solution, in turn have cuts 12c that can open through bending, offset with respect to the cuts of the base 11 so as to not jeopardise the pneumatic seal.

The base 1 1 and the cover 12 are then mutually secured through engagement of pins, that are not represented, inside holes 11d that are distributed on the side pieces 11b and in arc-shaped slots 12d correspondingly formed in the side pieces 12b. The sliding of the pins in the slots 12d indeed makes it possible for there to be the bending until a certain arc-shape is obtained which can be optimised according to the requirements.

At the two longitudinal ends the body 1 comprises respective heads 13 which complete its surface development, so that a closed chamber 14 is formed inside it. The chamber 14 is intended to house a pneumatic depression and it opens externally through a distribution of suction holes 11e that open up extensively and regularly on the entire working wall 11a. Correspondingly to the holes 11e the abrasive sheet 2 bears an identical distribution of holes 21 so as to allow the suction flow to pass.

The connection between the base 11 and the cover 12 is generally such as to obtain a seal that avoids pneumatic leaks, through suitable gaskets according to what is obvious to a man skilled in the art.

The depression inside the chamber 14 is obtained as a result of holes 12e formed in the cover wall 12a. The holes 12e are aligned on the central longitudinal axis of the wall 12a (and of the body 1 ), and are equally spaced in a number that fundamentally depends upon the length of the body itself. In the variant embodiment of figures 1 and 2 it is foreseen for there to be only two holes, whereas in the variant according to figures 3 and 4 it is foreseen for there to be four holes. The criterion for selecting the number of holes is that of having an even distribution of the depression over the entire development of the chamber 14, considering that for such a purpose the distance (pitch) between one hole and the other, assuming a suction power selected in the order of 1200-1400 W (see further on in the description), must not exceed 80 cm.

A T-joint or manifold 5 is pneumatically connected to each hole 12e, being mechanically anchored to the cover wall 12a through a perforated counter-plate 15. Each manifold projects from the cover wall with a central arm 5a and further comprises lateral arms 5b that indeed extend in a T shape from the central arm 5a parallel to the wall and at a certain distance from it. All the arms have a tubular structure, the lateral arms being aligned in the longitudinal direction. Thanks to such a configuration the manifold, in addition to the pneumatic function, can advantageously carry out the function of a comfortable gripping of the tool for moving it.

Among the various manifolds 5 two special ones can be distinguished, in this case, but not necessarily, those at the end of the series. In the example of figures 1 and 2 such two special manifolds are indeed the only ones, whereas in the other example between them there are other intermediate ones (two in this case). The two special manifolds are indicated with reference numerals 51 and 52, and are respectively an inlet manifold, that in this case can also be identified as head manifold, and a tail manifold. The tail manifold 52 has one of the two lateral arms 52b', namely the one facing the adjacent end of the body 1 , shut by a closing wall, and is therefore blind. The head manifold 51 is the one of which a lateral arm 51 b', also in this case facing the adjacent end of the body, is pneumatically connected with a flexible duct 7, connected or adapted to be connected at its opposite end to a source of depression of the known type, not represented.

Therefore, it is through the head manifold 51 that the suction flow reaches the tool, and is then transmitted from it to the other manifolds in series through flexible pipe segments 6 that join two by two the mutually facing lateral arms 51 b, 5b of consecutive manifolds, up to the tail manifold 52. In such a way the suction reaches and involves the entire chamber 14, determining a suction flow that is localised in various points of the chamber, being effective on the entire working wall 11a.

Again in connection with the head manifold 51 and its lateral arm 51b' for connecting to the flexible duct 7, such an arm has the further feature of a flow regulating passage 51c, the extent of opening/closing of which can be simply regulated through hand obstruction, leading to a decrease/increase in the suction power. As an alternative, the passage 51c can also be obtained on a portion of the lateral arm that can slide inside a fixed portion, so that a greater or lesser displacement of the sliding portion determines a greater or lesser obstruction of the hole.

A window 12f on the covering wall 12a, shut by a removable plug 8 is finally formed between the tail manifold 52 and the respective end of the body 1 so as to promote the removal of possible residual dusts that have accumulated inside the chamber 14.

Thanks to the configuration of the manifolds according to the invention, there is thus the possibility of obtaining a very long tool, up to three metres and more, in any case keeping an effective suction capability. It is thus possible to work on large surfaces, possibly also following curvatures precisely and without undulations thanks to the preferred variant with the flexible body 1 , without losing the suction advantages that, it is worth reminding, has an important role in protecting the health of the workers, in decreasing the consumption of abrasive paper, in improving the precision and the finishing of the sanding (the suction ensures that no residue is formed between the paper and the surface to be machined, with consequent risk of scratching or in any case alteration of the abrasive quality).

The fact that the manifolds 5, 51 , 52, again according to the preferred embodiment illustrated, can also be used as handles makes the tool particularly compact and easy to handle, in turn with positive consequences on the quality of the result. The fact that the tool has a single attachment point and in general a light structure despite its length positively contributes towards its good handling. As already mentioned the flexibility of the body 1 can represent one advantageous characteristic, but the main accomplishment of the invention can be achieved also with a rigid body 1 in the straight configuration.

The holes 21 on the paper 2 preferably have a distribution in orderly arrays so as to involve, as already mentioned, in an extensive and regular manner, the entire working wall, with holes that are spaced apart from one another by a few tens of mm. With reference in particular to figure 5, an advantageous and preferred distribution foresees a spacing (pitch) DL in the longitudinal direction of 70mm, with four longitudinal arrays of holes of which two central ones that are not offset with respect to one another and two side arrays extending along respective side edges, which are offset by half a pitch with respect to the central arrays. The (crosswise) distance between the central arrays DTc is equal to around double the distance DTf between a side array and the closest central array (for example and advantageously DTc=46mm, DTf=23mm).

The paper according to the invention thus has an elongated band configuration that is new with respect to analogous disposable materials currently on the market, indeed due to the new elongated structure of the device. According to the invention, there will be perforated strips of abrasive paper having a width of between 7 and 15 cm and a length of at least 80 cm as spare parts. Of course, the same size parameters of the band and of the distribution of holes will be analogously provided for on the working wall 11a in a preferred and advantageous dimensional variant of the tool.

Returning now to the structural shape of the tool, the special inlet manifold can also be arranged, as mentioned, not at a head of the body but in an intermediate position, in this case being it necessary to use a shape other than the T shape, wherein such a different shape is not illustrated here but is in any case obviously clear (two lateral arms for connecting to the other manifolds, and a further arm or attachment for connecting to the suction feed). As far as the body of the tool is now concerned, possible constructive alternatives, in replacement of the side pieces 12b, to ensure that the body is flexible, have been already mentioned. One of such alternatives is exemplified by the embodiment of figures 6 and 7, to which reference will now be made without describing again same parts or parts corresponding to those of the first embodiment, all the more so considering that these parts are indicated with corresponding numerals. In this case therefore, the base 111 and the cover 112, without the heads 113, are simple flat walls (working wall, and cover wall respectively), made from compact polycarbonate, joined by side pieces 116 made from a flexible and elastic material such as a synthetic rubber (for example expanded EPD rubber mixed with chloroprene) and with an external padding in the form of a covering case 103 made from synthetic fabric.

The casing ensures the pneumatic seal and provides for, or incorporates, the connection means (such as Velcro ^® ) for the sheet of perforated abrasive material. The side pieces can possibly have recesses in them, like in the example, so as to avoid obstructing the outermost suction holes. The attachment of the sleeves 151 , 152 is obtained through brackets 1 5 that in this case rise from the inner face of the base 101 , in any case ensuring the appropriate passage section of the pneumatic flow. Thanks to this solution, productively also more simple and cost-effective than the previous one, it is possible to achieve a greater curvature of the body, with an elastic return to the straight configuration without permanent deformations.

The present invention has been described thus far with reference to its preferred embodiments. It should be understood that there can be other embodiments that belong to the same inventive core, all within the scope of protection of the claims here attached. In particular, the constructive solutions for obtaining the body 1 (with it also being possible to include internal crosswise partition walls for physically dividing the chamber 14 in many localised suction areas), the mechanical configuration of the manifolds and so on, may be object of other variants.