Flexible abrasive for polishing surfaces

Abstract

A flexible abrasive (10) with a preset shape corresponding to the shape of the operating head of a machine tool such as a sanding machine and comprising a first support (16) made from a woven or non-woven material where a lower surface can be fixed to a backing plate or a pad of the operating head. The abrasive surface is made from at least two strips (20-23) applied side by side and parallel to each other and where the second support (11) of each strip (20-23) is separately fixed on the first support (16), and where the abrasive surface (18) is shaped so that it can be applied to the backing plate or pad of the operating head.

Claims

1. A method for manufacturing a flexible abrasive for polishing surfaces, said method comprising: providing a first support made from a woven or non-woven material permitting the aspiration of dust, where the lower surface of said first support can be fixed to a backing plate or a pad of an operating head of a machine tool such as a polishing machine; providing at least two rectilinear abrasive strips, each strip comprising a second support on which abrasive grits are applied by means of a first resin, wherein the strips have different grits in respect of each other; applying separately said at least two rectilinear abrasive strips to said first support at a predetermined distance from each other, in such a way that said strips are parallel and adjacent to each other and define at least one channel for carrying away the dust generated during work; shaping said support with said strips applied thereto in order to form a flexible abrasive whose shape corresponds to the shape of said operating head of a machine tool such as a polishing machine.

2. The method according to claim 1, wherein at least one strip also comprises a plurality of holes which form passages for the dusts and wastes formed during operation of the machine tool, and wherein the holes have a preset size and are separated from each other by a preset distance in order to prevent any clogging of the abrasive surface and/or the holes during use of the abrasive element.

3. The method according to claim 1, wherein the second support is made from paper or plastic film or from woven or non-woven material or similar, whereby said second support is applied to said first support by means of an adhesive.

4. The method according to claim 1, comprising applying a second resin to the second support, wherein the second resin holds for the abrasive grits in place.

5. The method according to claim 4, wherein an anti-clogging agent applied on top of the resin.

6. The method according to claim 1, wherein said flexible abrasive is either shaped as a disc, or as a delta or as a sheet of a plurality of parallel stripes separated by a plurality of channels.

7. The method according to claim 1, wherein the strips with different grits have different surface colours.

8. The method according to claim 1, wherein in the abrasive surface covers between 60% to 99% of the total surface of the backing plate or pad of the head and that the space between the strips comprises between 1% and 40% of the total surface.

9. The method according to claim 1, wherein the first support is made from nylon or polyester Velcro? with a weight between 45 and 300 g/m2.

10. The method according to claim 1, wherein the first support has a lengthways elongation to break point between 1% and 450% and/or a crossways elongation to break point between 1% and 450%.

11. The method according to claim 1, wherein the strips are made from a band having a width of at least 2.5 cm.

Description

DESCRIPTION OF THE DRAWINGS

(1) Other features and advantages of the invention will become clear on reading the description given below of one embodiment, provided as a non-binding example, with the help of the accompanying drawings, in which:

(2) FIG. 1 is a cross-section of the flexible abrasive element according to the present invention in its entirety.

(3) FIG. 2 shows a front view;

(4) FIG. 3 is a front view similar to that in the previous figure with the difference that the abrasive part has holes;

(5) FIGS. 4 and 5 are diagrams showing the flexible abrasive according to the invention with a triangular shape, with and without holes;

(6) FIGS. 6 and 7 are diagrams showing the flexible abrasive according to the invention in a sheet form, with and without holes.

DESCRIPTION OF ONE EMBODIMENT OF THE INVENTION

(7) In FIG. 1 the number 10 indicates in its entirety the flexible abrasive according to the present invention made from a plurality of strips 20, arranged adjacent and parallel to one another and applied to a support 16 in the shape of a disc or other suitable shapes.

(8) Each strip 20 can have a plurality of holes and comprises a support 11 (made from paper, woven or non-woven fabric or plastic or similar film) to which the abrasive grits 14 are applied by means of a first resin 12 and further held in place by means of a second resin 13.

(9) A anti-clogging layer 15 can be applied to the strips in both versions, with or without holes.

(10) The strips in the version shown in FIG. 3 have holes 17 whose shape, size and number depend on the application, the grit type and the support type. The strips 20 are applied with adhesives or other fixing systems to a woven or non-woven fabric support 16 which has eyelets which enable fixing to the backing plates or pads with Velcro.

(11) These strips 20 can be applied to their support with adhesives or other fixing systems and also to woven or non-woven supports and supports made from sponge, paper, plastic film or similar or in any combination of these. These surfaces can have an adhesive treatment or a self-adhesive layer, for fixing to the backing plates or surfaces without Velcro, consisting of what is commonly known as PSA (pressure sensitive adhesive).

(12) A support 16 made from woven or non-woven fabric fitted with strips prepared in this way and usually applied with adhesive to the support. This is then shaped to form discs as shown in FIGS. 2 and 3, or triangles as shown in FIGS. 4 and 5, or sheets as shown in FIGS. 6 and 7 so as to form an abrasive element indicated in its entirety by the reference number 10.

(13) The abrasive element 10 with a preset shape corresponding to the shape of the operating head of a machine tool such as a sanding machine comprises: a first support 16 made from a woven or non-woven material where a lower surface can be fixed to a backing plate or a pad of the operating head; a series of strips 20-23 adjacent and parallel to each other where each strip has a second support 11 applied to the first support 10 and where the upper surface of each abrasive strip 20-23 has a plurality of abrasive grits 14 applied to the second support by a first resin 12 and fixed there by a second resin 13; an anti-clogging layer 15 can if required be fixed on the second resin 13.

(14) The abrasive surface 18 of the abrasive element 10 is therefore made for a series of strips 20-23 parallel and adjacent to one another.

(15) According to one of the advantageous characteristics of the invention, the strips 20-23 can be positioned on the first support 16 separated from each other by a preset distance L to form at least one channel 24, or advantageously a series of parallel channels, for aspirating the dusts and wastes during operation, whose bottom is formed by the upper surface of the first support 16 and whose walls are formed by the thicknesses of the two adjacent strips.

(16) Each strip 20-23 can also comprise a plurality of holes 17 which form passages for the dusts and wastes formed during operation of the machine tool, and these holes 17 have a preset size and are separated from each other by a preset distance in order to prevent any clogging of the abrasive surface 18 defined by the strips during use of the abrasive element 10.

(17) The second support 11 is made from paper or plastic film or from woven or non-woven material or similar.

(18) The woven or non-woven material 16 which forms the first support is not subject to any specific restrictions regarding the type of material but it must be flexible, permit the aspiration of dusts and it must have eyelets or other fastening systems which permit its fixing to the backing plate or the Velcro surface. The base woven or non-woven material could be, for example, Velcro with a weight of between 45 and 300 g/m.sup.2 made of nylon or polyester.

(19) The woven or non-woven material must have a lengthways elongation to break point between 1% and 450% and a crossways elongation to break point between 1% and 450%.

(20) In addition to woven or non-woven material it is also possible to use sponge, paper, plastic film or similar or a combination of these. These surfaces can have an adhesive treatment or a self-adhesive layer, for fixing to the backing plates or surfaces without Velcro, consisting of what is commonly known as PSA (pressure sensitive adhesive).

(21) The flexible abrasive is formed by a support layer which can be paper, plastic film, woven material or similar to which adhesives or bonding resins of the phenolic, epoxy or similar types are applied. The purpose of these resins is to fix the abrasive grit to the support. The abrasive grit can be made from aluminium oxide, silicon carbide, zirconium, ceramics or similar. The grit is consolidated on the support by a further layer of adhesive or bonding resin of the phenolic, epoxy or similar type. The resins can also contain anti-clogging agents. Alternatively, an additional layer consisting of an anti-clogging agent such as calcium stearate can be applied.

(22) The shape and dimensions of the abrasive strips can vary depending on, the application and the abrasive grit used. The abrasive strips can have straight or shaped edges. The abrasive strips must cover a surface of between 60% to 99% of the surface of the final abrasive product so that the space between the strips comprises between 1% and 40% of the total surface of the abrasive product.

(23) The holes, where present, in these strips increase the capacity to aspirate dust for the work surface and help to reduce working temperatures. The size, number and shape of the holes is not specified and is determined on the basis of the application type, the grit and the type of abrasive used. Where present, the holes on each strip should cover between 0% and 50% of the total surface.

(24) The abrasive product made in this way can be shaped to form discs, strips, deltas, triangles, sheets or other commercial or special shapes. These shaped products can be used manually mounted on pads or other types of support, can be used manually on tools, electric tools or compressed air tools or similar or can be used on semi-automatic or automatic machinery.

(25) The number of strips and the distance between them depends on the size and shape of the final product. In general, each strip covers between 5% and 70% of the total surface.

(26) The strips are manufactured in bands usually with a width of at least 2.5 cm. In addition the flexible abrasive 10 according to the present invention consists of strips mounted side by side which have grit of different sizes. This makes it possible to manufacture a flexible abrasive product which has different abrasive properties. In this case the strips making up the flexible abrasive can have different colours to facilitate identification by the user.

(27) The invention is described in more detail in the example embodiment which follows.

(28) Product 1

(29) Product 1 comprises a flexible abrasive in the form of abrasive strips with multiple holes applied to a disc-shaped support.

(30) The strips are prepared using a commercial product named Napoleon GF02-P320 and in this case made specifically in strips with multiple holes applied to a 150 g/m2 Velcro support with a polyurethane adhesive. This abrasive is then die-cut into discs with a diameter of 150 mm. The discs are applied to a soft interface.

(31) Product 2

(32) Product 2 comprises a commercial abrasive disc named Napoleon GF02-P320. The disc has a diameter of 150 mm, is without holes and is mounted on a Velcro support.

(33) Product 3

(34) Product 3 comprises a commercial abrasive disc named Napoleon GF02-P320. The disc has a diameter of 150 mm, has six holes and is mounted on a Velcro support.

(35) Product 4

(36) Product 4 comprises a commercial abrasive disc named Napoleon GF02-P320. The disc has a diameter of 150 mm, has 15 holes and is mounted on a Velcro support.

(37) A PUTTY surface was prepared with a Mipa P99 Multi-Star bi-component putty (PE universal putty).

(38) A PRIMER surface was prepared with a Mipa 2K-Primer AZ primer.

(39) The surface to be machined was a curved metal sheet, 0.8 mm thick.

(40) The compressed air power tool used to sand the surfaces was a Rupes Skorpio RH 156A orbital sander set to 11,000 rpm with a 6 mm orbit, a diameter of 150 mm. A medium backing pad was used. The pneumatic aspiration was on.

Removal Rate

(41) TABLE-US-00001 TYPE PRODUCT # Initial weight [g] 1 MIN [g] 2 MIN [g] 3 MIN [g] TOT [g] Dust [g] PRIMER 1 2436 2433 2430 2427 9 n/a PRIMER 2 2528 2526 2523 2520 8 n/a PRIMER 3 2245 2243 2240 2238 7 n/a PRIMER 4 2448 2446 2443 2441 7 n/a PUTTY 1 2545 2537 2534 2528 17 0.4 PUTTY 4 3244 3238 3234 3231 13 3.2 PUTTY 3 3231 3224 3220 3217 14 2.5 PUTTY 2 2529 2522 2518 2514 15 1.1

(42) The results in the table above show that the flexible abrasive according to the present invention has a high material removal rate. Product 1 is shaped to and follows the surface and therefore makes it possible to use the entire surface of the disc during sanding. This makes it possible to remove a greater quantity of material in the same sanding time.

(43) The difference in removal rates is greater when sanding putty, an operation where a high removal rate is a critical parameter. It is interesting to note that the amount of dust left on the work surface by multi-hole strips is much less in comparison with no-hole or 15-hole discs (Products 2, 3 and 4). It was not possible to measure the amount of residual dust after sanding primer.

(44) Finish

(45) Surface roughness was measured using a Taylor Hobson Surtronic Duo portable roughness meter. Surface roughness was measured after the removal rate test on four different, representative points of the surface.

(46) The table below shows the sanding results after three minutes on panels prepared with primer and putty.

(47) TABLE-US-00002 GRAIN- 1 2 3 4 AVERAGE PRODUCT # FORMAT GRIT Ra ?m Rz ?m Ra ?m Rz ?m Ra ?m Rz ?m Ra ?m Rz ?m Ra ?m Rz ?m After 3 minutes polishing on PRIMER 2 ?150 P320 0.39 2.40 0.41 3.10 0.40 2.80 0.46 3.20 0.42 2.88 3 ?150 P320 0.42 2.75 0.39 2.50 0.44 3.10 0.49 3.50 0.44 2.96 4 ?150 P320 0.49 3.44 0.44 3.91 0.40 2.85 0.50 3.54 0.46 3.44 1 ?150 P320 0.34 2.30 0.43 2.70 0.37 2.60 0.44 3.20 0.40 2.70 After 3 minutes polishing on PUTTY 4 ?150 P320 0.82 5.20 0.89 6.50 0.80 4.92 0.78 4.31 0.82 5.23 3 ?150 P320 0.79 5.00 0.80 4.90 0.67 4.60 0.93 5.80 0.80 5.08 2 ?150 P320 0.88 5.50 0.75 4.90 0.72 4.80 0.76 4.60 0.78 4.95 1 ?150 P320 0.78 4.20 0.74 5.30 0.78 5.30 0.71 4.70 0.75 4.88

(48) As the table shows, on PRIMER and on PUTTY the roughness readings of the abrasive strips in disc format (Product 1) are on average better than those for equivalent products in different formats.

(49) Longevity

(50) Product longevity was measured as the total sanding time on putty up until clogging took place.

(51) TABLE-US-00003 Product # 1 2 3 4 Time 6 minutes 5 minutes 4 minutes 3 minutes 25 seconds 10 seconds 25 seconds 10 seconds

(52) As the results show, Product 1 had a markedly greater longevity in comparison with competing products. This was due to the space between the abrasive strips and the holes in the strips which facilitate better aspiration of the dust.

(53) The invention is described above with reference to a preferred embodiment. It is nevertheless clear that the invention is susceptible to numerous variations which lie within the scope of its disclosure, in the framework of technical equivalents.