EP3725461A1

EP3725461A1 - A circular-shaped abrasive device

Info

Publication number: EP3725461A1
Application number: EP20020163.0A
Authority: EP
Inventors: Massimo Milini; Elena Scattolon
Original assignee: Alesia Inc Srl; Tt International Srl
Current assignee: Alesia Inc Srl; Tt International Srl
Priority date: 2019-04-15
Filing date: 2020-04-08
Publication date: 2020-10-21
Anticipated expiration: 2040-04-08
Also published as: EP3725461B1; IT201900001286U1

Abstract

A circular-shaped abrasive device (10) configured to rotate around its own centre of rotation (1), and comprising a substantially flat front surface (2) with a plurality of openings. The openings comprise a series of through holes (4) which are positioned on the front surface (2) at areas surrounding the points identified by the intersection of a first set of geometric lines, formed of concentric circumferences (5) coplanar to the front surface (2) and having a centre of symmetry coinciding with the centre of rotation (1) of the abrasive device (10) and three second sets (7, 7', 7") of geometric lines, each formed of concentric ellipses (6), coplanar to the front surface (2).

Description

The present finding refers to a circular-shaped abrasive device.
More specifically, the present finding refers to an abrasive device configured to be placed in rotation around its own centre of rotation and comprising a plurality of openings.
In the field of surface finishing, in particular in the machining of composite materials, wood, vehicle bodies or even in the nautical industry, abrasive devices of various shapes and sizes can be used. These devices generally have at least a portion of abrasive surface, suitable for contact with a respective surface to be finished belonging to the object being machined. The abrasive surface of the abovementioned devices has a particular hardness, which is needed to sand resistant and robust materials, and is therefore made of a support bearing materials with suitable hardness characteristics, such as minerals, diamonds and/or specially made synthetic substances.
The abrasive devices belonging to the prior art are generally operated by appropriate drive devices in order to automate their movement and allow a more effective abrasive action.
In particular, in the case of circular-shaped abrasive devices, the drive devices are designed to allow the abrasive device to rotate around its own centre of rotation and, if necessary, this movement is made in association with an orbital movement. In this way the abrasive surface of the device, placed in movement and in contact with the surface to be finished, carries out the sanding or a generic finishing of the same. Due to this action of mutual contact between the abrasive surface of the device and the surface of the object to be finished, dust is created during the finishing process, which consists essentially of residues of the material abraded from the surface being machined.
In this context, abrasive devices with openings are known of so as to allow the passage of such dust into a collection area, which may be present inside said drive apparatus. In some cases, a forced suction may be provided, suitably implemented by special systems on the drive apparatus, in order to facilitate the channelling of dust through the openings, towards the aforementioned collection area.
Circular-shaped abrasive devices belonging to the prior art are, however, dimensioned so as to have an extensive diameter of the abrasive surface, so as to have a large extension of the abrasive surface available for finishing operations.
In addition, some of the known abrasive devices have openings of different sizes, arranged sparsely on the surface of the device and/or in such a way that openings with a larger diameter are placed in the peripheral areas of the surface.
In these abrasive devices the dust is partly removed from the machining area by passing through the openings; however, this removal process is not completely efficient and is therefore unsatisfactory, as part of the dust escapes from the machining area causing undesirable dirt in the surrounding area, as well as the need to increase the measures for proper protection of the respiratory tract of the operators performing finishing operations.
Additionally, some of the dust generated by the machining process remains in this area, in particular but not exclusively in an area close to the centre of rotation of the device in the interface between the abrasive surface of the device and the surface of the object being machined, leading to a substantial reduction in the abrasive property of the device and therefore an inefficiency of the finishing process carried out by it.
The purpose of the present finding is to overcome the drawbacks complained of above.
More in particular, the purpose of the present finding is to provide a circular-shaped abrasive device that allows an optimal removal of the dust resulting from the finishing operations.
Another purpose of the finding is to provide an abrasive device that has an improved ease of use, even for finishing operations on surfaces with different curvatures and in any case of complex shape.
Lastly, the purpose of the present finding is to create an abrasive device with an optimised arrangement of the openings present on the abrasive surface of the same, which substantially facilitates the removal of dust from the machining area and the conveyance of the same to an appropriately provided collection area, improving the quality and efficiency of the machining and the salubrity of the environment surrounding the machining area.
These and other purposes are achieved by the abrasive device of the present finding according to the main claim.
The construction and functional characteristics of the abrasive device of the present finding will be more clearly comprehensible from the detailed description below in which reference is made to the appended drawings/diagrams which show a preferred and non-limiting embodiment and wherein:

figure 1 schematically represents a front view of the abrasive device of the present finding, according to a preferred embodiment;
figure 2 represents a schematic view of a preferred arrangement of the openings on a front surface of the device according to the present finding, in which the geometrical elements suitable for the definition of such arrangement are highlighted.

With initial reference to the appended figures, the abrasive device 10 according to the present finding is made according to a preferably circular conformation and is configured to be placed in rotation around its own centre of rotation 1 by means of drive apparatus (not shown in the figures) which can be mechanically connected to such device 10.
The abrasive device 10 comprises a front surface 2, substantially flat and abrasive, which is provided with a plurality of openings, which cross the entire thickness of the device and are suitable for placing in fluidic communication a front area of the abrasive device 10 with a rear area thereof i.e. between the area near which the operations for which the device 10 is designed are carried out and an area for the collection of machining residues or dust.
The openings comprise a series of through holes 4, which are positioned on the front surface 2 at areas surrounding points which are geometrically identified by the intersection of suitably configured geometric lines.
In particular, as shown in fig. 2, a first set of geometrical lines is identified, formed of concentric circumferences 5 and coplanar to the front surface 2 of the device 10; preferably the circumferences 5 have a centre of symmetry coinciding with the centre of rotation 1 of the abrasive device 10.
Furthermore, second sets 7, 7', 7" of geometrical lines are identified, each of which is formed of concentric ellipses 6, and coplanar to the front surface 2 of the device 10.
In the preferred embodiment illustrated, each of said second sets 7, 7', 7" comprises concentric ellipses 6, the main axes of which lie on a respective half- line 8, 8', 8", originating in the centre of rotation 1 of the abrasive device 10. Preferably the ellipses 6 that form each of said second sets 7, 7', 7" are four in number.
In a preferred embodiment the ellipses 6 are arranged, for each of the second sets 7, 7', 7", at a substantially constant distance from each other.
Preferably, the half-lines 8', 8', 8" form angles with each other, having a vertex in the centre of rotation 1, the amplitude of which is about 120°. This creates a homogeneous and symmetrical distribution of the openings over the entire front surface 2.
The multiple openings further comprise substantially circular, abutment elements 9, which are configured to allow precise and accurate centring of the abrasive device 10 on the drive apparatus.
In a preferred embodiment the centre of the abutment elements 9 is placed on the half-lines 8', 8', 8" and/or on the extension thereof. Preferably, said abutment elements 9 have a diameter, also equivalent, of about 4 mm or more.
Preferably, the multiple openings of the abrasive device 10 comprise a number of through holes 4 greater than 50 and less than 20.
The openings on the front surface 2 are configured to allow the passage of waste material from a machining area adjacent to the front surface 2 to a collection area in the abrasive device drive apparatus, during use of the same in finishing operations.
Advantageously, the through-holes 4 located near the centre of rotation 1 are designed to be wider than the through-holes 4 on the remaining front surface 2. In this way, the dust generated during finishing operations is mainly removed in this area of the front surface 2 of the abrasive device 10.
This possibility is extremely convenient since the tangential speed of the points relative to the abrasive surface of the areas closest to the centre of rotation 1 is lower than the tangential speed of the points furthest from it; for this reason, the effectiveness of the abrasive action increases as it moves away from the centre of rotation 1 until it is maximum in the areas furthest from it. The provision of larger through-holes 4 in the area adjacent to the centre of rotation 1 therefore makes it possible to remove most of the dust generated by the finishing process in this area so as to have a greater abrasive surface in the areas furthest from the centre of rotation 1, which are more efficient in the finishing operations.
Preferably the through-holes 4 which are arranged at a distance from the centre of rotation 1 of not more than about 20 mm, have a diameter of about 5 mm or more.
As said, the diameter of the through holes 4 located in the areas further away from the centre of rotation 1 is smaller than the diameter of the through holes 4 near it, as most of the dust present is collected in the openings near the centre 1 of the device 10. Preferably the measurement of the diameter of the through holes 4 located at a distance of at least 30 mm from the centre of rotation 1 is greater than about 1.5 mm and less than about 5 mm; even more preferably it is greater than about 2 mm and less than about 4 mm. In this way the available working area of the outer surface 2 is advantageously optimised, improving the efficiency of the finishing operations.
The front surface 2 is preferably circular and has a diameter that is preferably greater than about 130 mm and less than about 150 mm. According to this solution, abrasive devices 10 of limited size are obtained, suitable for finishing curved surfaces or complex shapes, also allowing a reduction of the machining time since more manageable and adaptable to multiple geometries. This conformation also entails advantages during the production of the abrasive devices 10 since it reduces processing waste.
The device 10 also has a rear surface configured to create a mechanical connection with respective drive apparatus of the abrasive device 10. This connection can be made by means of adhesive coupling or Velcro.
Despite the finding having been described above with particular reference to one of its embodiments, given solely by way of a non-limiting example, numerous modifications and variants will appear evident to a person skilled in the art in the light of the above description. The present finding therefore sets out to embrace all the modifications and variants which fall within the sphere and scope of protection of the following claims.

Claims

A circular-shaped abrasive device (10) configured to be placed in rotation around its own centre of rotation (1), said abrasive device comprising a substantially planar front surface (2) provided with a plurality of openings, characterised in that said plurality of openings comprises at least one series of through holes (4), positioned on the front surface (2) at areas surrounding the points identified by the intersection of:
- a first set of geometric lines, formed of concentric circumferences (5) coplanar to the front surface (2) and having a centre of symmetry coinciding with the centre of rotation (1) of the abrasive device (10); with

- three second sets (7, 7', 7") of geometric lines, each of which is formed of concentric (6) ellipses, coplanar to the front surface (2).
The abrasive device (10) according to claim 1, wherein each of such second sets (7, 7', 7") comprises at least four concentric ellipses (6) having major axes lying on a half-line (8, 8', 8") originating in the centre of rotation (1) of the abrasive device (10).
The abrasive device (10) according to claim 2, wherein said half-lines (8', 8', 8") form angles with each other, having a vertex in the centre of rotation (1), the amplitude of which is about 120°.
The abrasive device (10) according to claim 2 or 3, wherein said plurality of openings further comprises abutment elements (9), substantially circular in shape, the centre of which is placed on the half-lines (8, 8', 8") and/or on the extension thereof, said abutment elements (9) having a diameter, also equivalent, the size of which is greater or equal to approximately 4 mm.
The abrasive device (10) according to claim 1, wherein the multiple openings of the abrasive device (10) comprise a number of through holes (4) greater than 50 and less than 200.
The abrasive device (10) according to any of the claims from 1 to 5, wherein the through-holes (4) placed at a distance from the centre of rotation (1) of not more than about 20 mm, have a diameter of about 5 mm or more.
The abrasive device (10) according to any of the claims from 1 to 6, wherein the measurement of the diameter of the through-holes (4) which are placed at a distance of at least 30 mm from the centre of rotation (1) is greater than about 1.5 mm and less than about 5 mm.
The abrasive device (10) according to any of the preceding claims, wherein said front surface (2) is circular and has a diameter greater than about 130 mm and less than about 150 mm.
The abrasive device (10) according to any of the preceding claims, wherein said openings are configured to allow the passage of waste material from a machining area adjacent to the front surface (2) to a collection area made in the abrasive device drive apparatus (10), during use of said abrasive device.
The abrasive device (10) according to claim 9, further comprising a rear surface configured to create a mechanical connection by adhesive or Velcro coupling to said abrasive device drive apparatus (10).