SANDING MACHINE FOR WOODEN PRODUCTS AND RESPECTIVE SANDING TOOL

Abstract

 A machine for sanding surfaces of wooden products is described comprising: a support structure (12); at least one sanding unit (14) comprising at least one sanding device (16); and linear movement means (38, 40, 42) arranged to move the sanding device (16) along at least two axes (A, B, C) orthogonal to each other. The said sanding device (16) comprises at least one rotating sanding tool (18), driven by a respective motor (22) to rotate around its own rotation axis (D). The rotating sanding tool (18) is provided with an abrasive surface (20) which extends on a plane (P) substantially perpendicular to said rotation axis (D) and which is configured for performing the sanding and/or polishing of the surfaces of the wooden products. At least the abrasive surface (20) of the rotating sanding tool (18) has a plan shape, that is to say obtained on the plane (P), of a flat and convex geometric figure having three or more sides (20A, 20B, 20C, 20D) of equal length.

Description

[0001] The present invention generally relates to a machine for processing wooden products and, in particular, an improved sanding tool for a machine designed to sand and/or polish linear wooden products both in their raw state and provided with paints applied on the respective surfaces.

[0002] Sanding machines are known which are capable of sanding and/or polishing wooden products consisting, for example, of doors, furniture doors, table surfaces, etc. In general, these wooden products comprise flat surfaces parallel to each other, but they can also be provided with grooved shaping and/or raised surfaces. An example of this type of wooden products is given by the doors provided with "ashlar" type panelling.

[0003] In order to obtain the sanding and/or polishing of the flat surfaces of wooden products, the sanding machines are equipped with one or more sanding tools consisting of rotating discs, usually called "sanding pads". In order to obtain the sanding and/or polishing of the recessed and/or raised parts of the wooden products, the sanding machines instead need to be equipped with different types of tools, such as abrasive brushes. Known sanding machines are described, for example, in documents EP 2 123 396 A1 (in the name of the same applicant and on which the preamble of claim 1 is based), US 2017/057046 A1 and CN 107 030 554 A.

[0004] In terms of finishing, due to the different tools used, the two distinct sanding and/or polishing operations referred to above produce different results and are therefore not comparable. Consequently, a further manual finishing operation of the wooden product is always necessary, which is typically performed with the so-called roto-orbital sanders or with other manual tools, such as abrasive sponges.

[0005] An object of the present invention is, therefore, to provide a sanding machine and a respective improved sanding tool which are capable of solving the aforementioned drawbacks of the prior art in an extremely simple, economical and particularly functional way.

[0006] In detail, it is an object of the present invention to provide a sanding machine and a respective improved sanding tool which are capable of reliably performing sanding and/or polishing operations both on the flat surfaces of a generic wooden product and on grooved and/or raised parts of this wooden product.

[0007] Another object of the present invention is to provide a sanding machine and a respective improved sanding tool which are capable of reliably performing sanding and/or polishing operations even inside cavities of a generic wooden product having a particular shape, such as cavities having 90° angles.

[0008] These and other objects according to the present invention will be achieved by providing a sanding machine and a respective improved sanding tool as set forth in claim 1.

[0009] Further features of the invention are highlighted by the dependent claims, which are an integral part of the present description.

[0010] The features and advantages of a sanding machine and a respective improved sanding tool according to the present invention will be clearer from the following exemplifying and hence non-limiting description, referring to the attached schematic drawings wherein:

Figure 1 is a side elevation view of a possible embodiment of the sanding machine for wooden products provided with a respective improved sanding tool according to the present invention;

Figure 2 is a side elevation view of the linear movement unit of the sanding tool of the sanding machine of Figure 1;

Figure 3 is a sectional view, obtained along line III-III of Figure 2, of the linear movement unit of the sanding tool of the sanding machine of Figure 1;

Figure 4 is a vertical sectional view of the sanding device that supports and rotates the sanding tool of the sanding machine of Figure 1;

Figure 5 is a top plan view of a first embodiment of the sanding tool of the sanding machine of Figure 1;

Figure 6 is a sectional view, obtained along line VI-VI of Figure 5, of the sanding tool of Figure 5;

Figure 7 is an exploded view of the main components of the sanding tool of Figure 5;

Figure 8 is a top plan view of a second embodiment of the sanding tool of the sanding machine of Figure 1;

Figure 9 is a sectional view, obtained along line IX-IX of Figure 8, of the sanding tool of Figure 8; and

Figure 10 is an exploded view of the main components of the sanding tool of Figure 8.

[0011] With reference in particular to Figure 1, a sanding machine for wooden products according to the present invention is shown. The sanding machine is indicated as a whole with reference number 10. The sanding machine 10 comprises a support structure 12 and at least one sanding unit 14 comprising in turn at least one sanding device 16. Linear movement means 38, 40, 42, which will be described in more detail below and are configured to move the sanding device 16 along at least two (preferably three) axes A, B, C orthogonal to each other, are, therefore, provided on the sanding machine 10.

[0012] The sanding device 16 comprises at least one rotating sanding tool 18, driven by a respective motor 22 to rotate around its own rotation axis D (see Figures 3 and 4). The rotating sanding tool 18 is provided with an abrasive surface 20 which extends on a plane P substantially perpendicular to the rotation axis D of this rotating sanding tool 18. This abrasive surface 20 is configured for performing sanding and/or polishing of the surfaces of the wooden products.

[0013] According to the invention, at least the abrasive surface 20 of the rotating sanding tool 18 has a plan shape, that is to say obtained on its development plane P, of a flat and convex geometric figure having three or more sides 20A, 20B, 20C, 20D of equal length. In particular, as shown in Figures 8 to 10, at least the abrasive surface 20 of the rotating sanding tool 18 has a plan shape of a Reuleaux triangle, wherein the three sides 20A, 20B, 20C of this Reuleaux triangle are curvilinear, convex with respect to the centre of gravity of the Reuleaux triangle and have the same length. Alternatively, as shown in Figures 5 to 7, at least the abrasive surface 20 of the rotating sanding tool 18 can have a plan shape of a square with substantially straight sides 20A, 20B, 20C, 20D.

[0014] As is known, a Reuleaux triangle is a plane curve of constant width obtained starting from an equilateral triangle, that is to say with three equal-length sides. On each side an arc of a circle is constructed with a radius equal to the length of the side itself, so that the effective sides 20A, 20B, 20C of this Reuleaux triangle are curvilinear. If rotated on its own development plane, a Reuleaux triangle covers an area approximately equal to the one of a square. Consequently, when the rotating sanding tool 18 is rotated around its own rotation axis D, the respective abrasive surface 20 is able to almost completely sand and/or polish grooved surfaces which are placed in the vicinity of walls which form a 90° angle.

[0015] Preferably, as shown in the plan views of Figures 5 and 8, the abrasive surface 20 of the rotating sanding tool 18 is provided with three or more rounded shape edges 24A, 24B, 24C, 24D, wherein each edge 24A, 24B, 24C, 24D constitutes a respective vertex of the flat and convex geometric figure, that is to say of the Reuleaux triangle or of the square. Again, preferably, each edge 24A, 24B, 24C, 24D has a circular arc profile with a radius between about 1 mm and about 5 mm, preferably about 3 mm. With a radius of each edge 24A, 24B, 24C, 24D of the abrasive surface 20 equal to about 3 mm, the rotating sanding tool 18 is able to almost perfectly sand and/or polish 90° grooved edges.

[0016] As shown in particular in Figures 4, 6-7 and 9-10, the rotating sanding tool 18 has a plan shape which is compatible with the plan shape of the respective abrasive surface 20. In other words, the rotating sanding tool 18 comprises a metal plate 46, under which the abrasive surface 20 is mounted, where this metal plate 46 also has a plan shape which can be a Reuleaux triangle or a square.

[0017] The metal plate 46 of the rotating sanding tool 18 is preferably made of aluminium and has a preferred thickness of about 15 mm. The abrasive surface 20, instead, preferably consists of a rubbery sponge provided with Velcro-type connection means, so as to be adapted to receive a layer 48 of abrasive paper (Figures 7 and 10), also provided with Velcro-type connection means.

[0018] The metal plate 46 of the rotating sanding tool 18 can then be provided with at least one cavity 50 adapted to receive a corresponding pin 52 of the sanding device 16. Preferably, as shown in the figures, two cavities 50 and two corresponding pins 52 are provided. The engagement of each pin 52 in the corresponding cavity 50 allows to block the rotation of the rotating sanding tool 18. Furthermore, the rotating sanding tool 18 is operatively connected to the sanding device 16 in a non-rigid way, so as to allow the rotating sanding tool 18 itself, at the time of processing, to properly lean against and adjust to the surface of the wooden product.

[0019] The motor 22 which drives the rotating sanding tool 18 can preferably be connected to this rotating sanding tool 18 by means of at least one drive shaft 26 (Figure 3) and one gearbox 28, 30, 32, 34, 36. In detail, as shown in Figure 3, a first toothed wheel 28 of the gearbox is fastened on the drive shaft 26, which transmits motion to a second toothed wheel 30 and, in cascade, to a third toothed wheel 32, to a fourth wheel toothed 34 and finally to a fifth toothed wheel 36, obtaining a final ratio of 1:3 and the inversion of the incoming rotation, which allows the rotating sanding tool 18 to cover, while rotating, the square shape necessary to sand and/or polish recessed surfaces with 90° angles. The working speed of the rotating sanding tool 18 is preferably expected in a range from 50 rpm to 100 rpm.

[0020] In any case, other motion transmission systems can be provided between the motor 22 and the rotating sanding tool 18 which differ from the mechanical gear transmission system described above. For example, the movement of the rotating sanding tool 18 could be electronically controlled, through the programmable logic controller or PLC (not shown) of the machine 10, so as to give this rotating sanding tool 18 movements suitable for particular processing on wooden products.

[0021] The rotating sanding tool 18 is provided, in a position opposite to the position in which its abrasive surface 20 is placed, with at least one quick coupling element 44 for releasable connection of said rotating sanding tool 18 to the respective gearbox 28, 30, 32, 34, 36. The quick coupling element 44 allows the quick change of the rotating sanding tool 18 to be performed both in manual mode and in automatic mode if the sanding machine 10 is set up for automatic change of the rotating sanding tool 18.

[0022] With reference in particular to Figures 1 to 3, it should be noted that the linear movement means 38, 40, 42 of the sanding machine 10 can comprise:

• a first motorized movement device 38, such as a first plate 38 slidable on linear guides integral with the support structure 12, which is arranged to move the sanding device 16 with respect to this support structure 12 along a first substantially horizontal axis A; and
• a second motorized movement device 40, such as a second plate 40 slidable on the first plate 38, which is arranged to move the sanding device 16 with respect to the first motorized movement device 38 along a second axis B which is substantially vertical and perpendicular to the first axis A.

[0023] Furthermore, as shown in Figure 3, the linear movement means 38, 40, 42 of the sanding machine 10 can also comprise a third motorized movement device 42, which is arranged to move the sanding device 16 with respect to the second motorized movement device 40 along a third axis C which is substantially horizontal and perpendicular both with respect to the first axis A and with respect to the second axis B. In other words, the sanding device 16 and the respective rotating sanding tool 18 can be mounted on a linear movement unit 38, 40, 42 which allows three movements along a system of three orthogonal Cartesian axes A, B, C. The sanding machine 10 can therefore be equipped with an electronic control unit (not shown) which allows these movements to be electronically controlled, thanks to the presence of height and dimension detecting devices present on the sanding machine 10 itself, so as to allow the rotating sanding tool 18 to start processing at the points provided in the wooden product.

[0024] It has thus been shown that the sanding machine and the respective improved sanding tool according to the present invention achieve the objects highlighted above.

[0025] The sanding machine and the respective improved sanding tool according to the present invention thus conceived are however susceptible of numerous modifications and variations in any case, all of which falling within the same inventive concept; furthermore, all the details can be replaced by technically equivalent elements. The scope of protection of the invention is therefore defined by the attached claims.

Claims

1. A machine (10) for sanding and/or polishing surfaces of wooden products, the machine (10) comprising:

- a support structure (12);

- at least one sanding unit (14) comprising at least one sanding device (16); and

- linear movement means (38, 40, 42) arranged to move said sanding device (16) along at least two axes (A, B, C) orthogonal to each other,

wherein said sanding device (16) comprises at least one rotating sanding tool (18), driven by a respective motor (22) to rotate around its own rotation axis (D), said rotating sanding tool (18) being provided with an abrasive surface (20) which extends on a plane (P) substantially perpendicular with respect to said rotation axis (D) and which is configured for performing the sanding and/or polishing of the surfaces of said wooden products, the machine (10) being characterized in that at least the abrasive surface (20) of said rotating sanding tool (18) has a plan shape, that is to say obtained on said plane (P), of a flat and convex geometric figure having three or more sides (20A, 20B, 20C, 20D) of equal length.

2. The machine (10) according to claim 1, characterized in that at least the abrasive surface (20) of said rotating sanding tool (18) has a plan shape, that is to say obtained on said plane (P), of a Reuleaux triangle, wherein the three sides (20A, 20B, 20C) of said Reuleaux triangle are curvilinear, convex with respect to the center of gravity of said Reuleaux triangle and have the same length.

3. The machine (10) according to claim 1, characterized in that at least the abrasive surface (20) of said rotating sanding tool (18) has a plan shape, that is to say obtained on said plane (P), of a square with substantially straight sides (20A, 20B, 20C, 20D).

4. The machine (10) according to any claims 1 to 3, characterized in that the abrasive surface (20) of said rotating sanding tool (18) is provided with three or more rounded shape edges (24A, 24B, 24C, 24D), wherein each edge (24A, 24B, 24C, 24D) constitutes a respective vertex of said flat and convex geometric figure.

5. The machine (10) according to claim 4, characterized in that each edge (24A, 24B, 24C, 24D) has a circular arc profile with a radius between about 1 mm and about 5 mm, preferably about 3 mm.

6. The machine (10) according to any claims 1 to 5, characterized in that said rotating sanding tool (18) comprises a metal plate (46) which has a plan shape compatible with the plan shape of said abrasive surface (20).

7. The machine (10) according to claim 6, characterized in that said metal plate (46) is provided with at least one cavity (50) adapted to receive a corresponding pin (52) of said sanding device (16), wherein the engagement of said pin (52) in the corresponding cavity (50) blocks the rotation of said rotating sanding tool (18).

8. The machine (10) according to any claims 1 to 7, characterized in that said motor (22) is connected to said rotating sanding tool (18) by means of at least one drive shaft (26) and one gearbox (28, 30, 32, 34, 36), wherein said gearbox (28, 30, 32, 34, 36) preferably has a ratio of 1:3.

9. The machine (10) according to claim 8, characterized in that said rotating sanding tool (18) is provided, in an opposite position with respect to the position where said abrasive surface (20) is placed, with at least one quick coupling element (44) for releasable connection of said rotating sanding tool (18) to said gearbox (28, 30, 32, 34, 36).

10. The machine (10) according to any claims 1 to 9, characterized in that said linear movement means (38, 40, 42) comprise:

- a first motorized movement device (38), arranged to move said sanding device (16) with respect to said support structure (12) along a first substantially horizontal axis (A); and

- a second motorized movement device (40), arranged to move said sanding device (16) with respect to said first motorized movement device (38) along a second axis (B) which is substantially vertical and perpendicular to said first axis (A).

11. The machine (10) according to claim 10, characterized in that said linear movement means (38, 40, 42) further comprise a third motorized movement device (42), arranged to move said sanding device (16) with respect to said second motorized movement device (40) along a third axis (C) which is substantially horizontal and perpendicular both with respect to said first axis (A) and with respect to said second axis (B).

12. The machine (10) according to any claims 1 to 11, characterized in that said rotating sanding tool (18) comprises a metal plate (46) preferably made of aluminum, and in that said abrasive surface (20) consists of a rubbery sponge provided with Velcro-type connection means and is adapted to receive a layer (48) of abrasive paper, also provided with Velcro-type connection means.

Drawing