Flap wheel

Abstract

The current inventing relates to a flap wheel for abrading contoured surfaces on a substrate, the flap wheel comprising; - a central hub defining a central wheel axis of rotation, - a plurality of flexibly-acting working members being attached to the central hub and extending radially from the central hub for providing abrasive action on the substrate at a peripheral side of the working members opposite the central hub, each working member having an outer profiled surface comprising at least a curved section for substantially matching the contoured surface on the substrate, wherein the flexibly-acting working members comprise abrasives comprising diamond or any other suitable super-abrasive material.

Description

[0001] Flap wheel

[0002] Field of the invention

[0003] The present invention relates to a flap wheel for abrading surfaces on a substrate, the flap wheel comprising;

[0004] - a central hub defining a central wheel axis of rotation, and

[0005] - a plurality of flexibly-acting working members being attached to the central hub and extending radially from the central hub for providing abrasive action on the substrate at a peripheral side of the working members opposite the central hub.

[0006] Background art

[0007] Flap wheels are known and use discrete packs of abrasive or polishing sheet materials referred to as flaps. An example of a known flap wheel is the KGS Hybrid® flap disc. The flaps of a flap wheel are mounted in a rotary hub that is driven by e.g. an electric motor. The hub normally has a standardized connection like a M14 connection, or a 22 mm bore. Flaps can be mounted to the hub in any suitable way, like hinged to the hub, fitted in slots in the periphery of the hub, which slots are usually axial, or attached to the hub by using a resin bond.

[0008] In operation the flap wheel is rotated with some pressure against the substrate that needs to be worked. The flaps are the wear replacement parts.

[0009] Flap discs can be used for sanding almost all materials, often they are used for (natural) stone, plastic, glass and metal. The flap disc main effect is material removal.

[0010] The abrasives in a flap wheel are usually metal bonded or resin bonded. The abrasives can contain diamond, silicon carbide or any other suitable abrasive. This results in fast material removal with a soft and smooth feel. Flap discs are available in different grit sizes, like from grit 50, 60, 120 and 200 up to 400.

[0011] US4275529A relates to a flap wheel having interleaved coated abrasive flaps and nonwoven flaps which contains more flaps compared to a usual flap wheel of the same diameter thereby providing a compacted or densified flap wheel. The highly compacted flap wheel is associated in US4275529A with increased grain efficiency, which is the quotient of the weight of material removed from a workpiece divided by the weight loss of the abrasive flap wheel during such removal.

[0012] There is room for improvement of prior art flaps, in particular with respect to accuracy of a surface of a substrate that is processed by the flap wheel.

[0013] To work contoured surfaces, polishing wheels are known. Such a rigid polishing wheel can abrade contoured surfaces on a substrate. After wearing, and even after minor wear, such a rigid polishing wheel does not impose the desired contoured shape to the substrate anymore. This problem is all the more present in case of working the substrate with a number of polishing wheels, which is normally the case. The reason therefore is that each of the plurality of polishing wheels does wear slightly different as compared to other wheels of the plurality of polishing wheels.

[0014] Summary of the invention

[0015] The present invention seeks to provide a flap wheel for abrading a surface on a substrate, wherein a shape or contour is imposed on a surface of a substrate in a more efficient manner, including faster and with better precision.

[0016] The present invention seeks to provide a flap wheel for abrading a surface on a substrate, wherein a problem associated with a known flap wheel is at least partly solved.

[0017] The present invention seeks to provide an alternative flap wheel for abrading a surface on a substrate.

[0018] Therefore, the present invention provides a flap wheel for abrading contoured surfaces on a substrate, the flap wheel comprising;

[0019] - a central hub defining a central wheel axis of rotation,

[0020] - a plurality of flexibly-acting working members being attached to the central hub and extending radially with respect to the central wheel axis of rotation for providing abrasive action on the substrate at a peripheral side of the working members opposite the central hub, each working member having an outer profiled surface comprising at least a curved section for substantially matching the contoured surface on the substrate, wherein the flexibly-acting working members comprise abrasives comprising diamond or any other suitable super-abrasive material.

[0021] Each working member having an outer profiled surface comprising at least a curved section for substantially matching the contoured surface on the substrate, and the flexibly-acting working members comprising abrasives comprising diamond or any other suitable superabrasive material provides a superior balance between processing time and accuracy of the contoured surface on the substrate.

[0022] The outer profiled surface includes a curved section or in an embodiment even a plurality of curved sections. The plurality of curved sections does preferably form a continuous contour. The working member may be or comprise an, other than the profiled surface, rectangular sheet which is well known for flap wheels. The working members, also known as flaps, being flexibly acting means that the working members have a certain degree of freedom to flap or flutter.

[0023] In an embodiment according to the invention, the flap wheel comprises subsequent flexibly-acting working members comprising different abrasives. The flap wheel comprising subsequent flexibly-acting working members comprising different abrasive provides all the more a superior balance between processing time and accuracy of the contoured surface on the substrate and in addition optimizes abraded volume and surface quality.

[0024] In an embodiment, the flap wheel according to the invention comprises a support system for maintaining the shape of at least one of the plurality of flexibly-acting working members, wherein the support system extends between adjacent flexibly-acting working members. The support system enables to maintain the shape of a working member and thus improves accuracy of the contoured surface on the substrate. The support system contacts the at least one working member in the direction of rotation. The support system contacts the at least one working member in the direction of rotation over substantially the entire surface of the working member to avoid out of plane deformation of the working member as much as possible. It is however conceivable that a small portion of the profiled surface protrudes with respect to the support system. In other words, the small portion of the profiled surface does not overlap with the support system and is not directly supported. The small portion may be less than 5% or even 1 % of a radius of the flap wheel.

[0025] The support system preferably only contacts the working member to support the working member. This improves freedom of movement and elastic deformation of the working member in the radial direction which in turn facilitates functioning as a flap. It is however conceivable that the support member is attached to the working member. This will on the one hand improve support of the working member and thus accuracy of the contoured surface on the substrate. On the other hand, freedom of movement and elastic deformation of the working member in the radial direction is then more dependent on the flexibility of the support system. In any case, the support system defines a minimum spacing between adjacent working members.

[0026] In an embodiment of the flap wheel according to the invention, the support system comprises a first layer comprising a non-woven material. The support system comprises a first layer that comprises a non-woven material contributes in maintaining the shape of the working member, in particular in a radial direction. In addition, stability is improved which in turn prevents out of plane deformation.

[0027] In an embodiment of the flap wheel according to the invention, the support system comprises a second layer different and separate from the first layer and comprising a foam material. The support system comprising a second layer different and separate from the first layer and comprising a foam material provides freedom to improve stability of the working member in radial direction and provides flexibility in a tangential direction. The combination of in short radial stability and tangential flexibility of the working member, results in an all the more improved precision of the contour that is imposed on the surface of the substrate. In other words, the second layer comprising foam assures that the working member is still able to function as a flap.

[0028] In an embodiment of the flap wheel according to the invention, the first and second layer are attached at opposite surfaces that extend radially in order to form a unity. The first and second layer forming a unit improves the effect of the combination of radial stability and tangential flexibility of the working member, resulting in an all the more improved precision of the contour that is imposed on the surface of the substrate. The first and second layer can be attached by adhesive bond, melt bond or any other suitable way of surface bond.

[0029] In an embodiment of the flap wheel according to the invention, the nonwoven material of the first layer is characterized by one or more of, a grit size between 130 and 170 mesh in particular about 150 mesh, a weight between 1400 and 1800 gram per square meter, in particular about 1600 gram per square meter. This contributes to maintaining the shape of the at least one working member, in particular in a radial direction. In addition, stability is improved which in turn prevents out of plane deformation of the at least one working member.

[0030] In an embodiment of the flap wheel according to the invention the foam material of the second layer comprises one or more of silicon and polyurethane, and the foam material of the second layer is characterized by a Shore A hardness of between 35 - 55. This all the more contributes to a uniform support of the at least one working member. In turn, this contributes to an improved precision of the contour that is imposed on the surface of the substrate.

[0031] In an embodiment of the flap wheel according to the invention, the second layer is different from the first layer in that a density of the second layer is lower compared to a density of the first layer. This all the more enables to improve the support of the at least one working member.

[0032] In an embodiment of the flap wheel according to the invention, a ratio of the density of the second layer and the density of the first layer is between 0,3 and 0,6, in particular about 0,4. It turned out that this ratio all the more enabled to improve the support of the at least one working member.

[0033] In an embodiment of the flap wheel according to the invention, the foam material of the second layer is characterized by a weight between 500 and 800 gram per square meter, in particular about 660 gram per square meter.

[0034] In an embodiment of the flap wheel according to the invention, the support system comprises abrasives. The support system comprising abrasives contributes to the abrasive action of the flap wheel. This also enables to use different abrasives as compared to the working members. This can add functionality to the flap wheel like for example a better surface quality of the contoured surface on the substrate.

[0035] In an embodiment of the flap wheel according to the invention, the support system comprises abrasives different from abrasives comprised in the plurality of flexibly-acting working members. As mentioned, this adds functionality to the flap wheel like for example a better surface quality of the contoured surface on the substrate.

[0036] In an embodiment of the flap wheel according to the invention, the plurality of flexibly-acting working members and / or the support system comprises electrically conductive material in electrically conductive connection with at least the central hub. The electrically conductive material reduces the amount of static electricity build up, which in turn reduces the risk of fire from charged dust particles.

[0037] In an embodiment of the flap wheel according to the invention, the support system comprises a pair of opposite disk members in contact with axial sides of the plurality of flexibly-acting working members in order to support and enclose the working member in an axial direction of the central hub, wherein a disk member of the pair of opposite disk members preferably comprises a foam layer and a rubber layer. The disk members improve support of the working members, and this results in turn in an all the more improved precision of the contour that is imposed on the surface of the substrate. The disk member overlaps as much as possible in a radial direction with the working members in order to maximize support. The disk member extends to between 60% and about 95% or even 100% of the length of the working member in the radial direction of the flap wheel.

[0038] In an embodiment of the flap wheel according to the invention, the outer profiled surface comprising a plurality of curved sections.

[0039] Short description of drawings

[0040] The present invention will be discussed in more detail below, with reference to the attached drawings, in which

[0041] fig. 1 A is a prior art rigid polishing wheel that can abrade contoured surfaces on a substrate; fig. 1B is a prior art flap wheel having a discrete pack of abrasive or polishing sheet materials referred to as flaps;

[0042] fig. 2 is an embodiment of a flap wheel according to the invention in a perspective view; fig. 3 is a detail of the flap wheel of fig. 2;

[0043] fig. 4 is a cross-sectional side view of the flap wheel of fig. 2; and fig. 5 is a further embodiment of a flap wheel according to the invention in a perspective view;

[0044] fig. 6 is a further embodiment of a flap wheel according to the invention in a perspective view;

[0045] fig. 7 is a detail of the flap wheel of fig. 6; and

[0046] fig. 8 is a detail of a working member in cross sectional side view.

[0047] Detailed description of figures

[0048] Figure 1A is a prior art rigid polishing wheel 1 that can abrade contoured surfaces on a substrate that is not shown. The polishing wheel 1 therefore rotates around the central axis 2 of the polishing wheel 1. The polishing wheel 1 has a curved surface 3 where abrasives are deposited. After wearing, and even after minor wear, the rigid polishing wheel 1 does not impose the desired contoured shape to the substrate anymore.

[0049] Figure 1B is a prior art flap wheel 4 having a discrete pack of abrasive or polishing sheet materials referred to as flaps 6. The flap wheel 4 has a central axis of rotation 5.

[0050] Now turning to an embodiment of a flap wheel 7 according to the invention with reference to figures 2, 3 and 4.

[0051] There is shown a flap wheel 7. The flap wheel 7 is configured for abrading contoured surfaces on a substrate that is not shown here.

[0052] Therefore, the flap wheel 7 comprises a central hub 22. The central hub defines a central wheel axis of rotation 13. In use, the flap wheel 7 rotates or is rotatable around the central wheel axis of rotation 13.

[0053] The flap wheel 7 comprises a plurality of flexibly-acting working members 18. The plurality of flexibly-acting working members is referred to with reference number 18. A single working member, or also flap, is referred to with reference number 10. The plurality of flexibly-acting working members may be attached to the central hub 22 in a form closed manner known per se. In this case, the plurality of flexibly-acting working members is attached to the central hub 22 by an adhesive connection. The adhesive can be one or more of a PU, TPU, or Epoxy based heat-and water-resistant adhesive. Here, the adhesive extends from the central hub 22 over approximately 20% of a radial length of the flaps 10. This all the more mutually attaches the flaps 10.

[0054] The plurality of flexibly-acting working members extending radially with respect to the central wheel axis of rotation 13. The plurality of flexibly-acting working members 18 provide abrasive action on the substrate at a peripheral side 14 of the working members opposite the central hub 22. Therefore, each working member has an outer profiled surface 16 comprising at least a curved section 24 for substantially matching the contoured surface on the substrate. The flexibly-acting working members 18 comprise abrasives comprising diamond. It is conceivable that the flexibly-acting working members 18 comprise any other suitable super-abrasive material like for example silicon carbide. Each working member has an identical outer profiled surface 16. In this case, the profiled surface 16 includes a single curved section 24. It is however conceivable that the profiled surface 16 includes multiple curved sections that do form a continuous contour.

[0055] The flap wheel 7 comprises subsequent flexibly-acting working members 10. All together, the working members fill and constitute the flap wheel 7. Subsequent flexibly-acting working members 18 may comprises different abrasives.

[0056] The flap wheel 7 comprises a support system 8, 9. The support system 8, 9 is configured for maintaining the shape of at least one working member 10 of the plurality of flexibly-acting working members 18. In this case it will be clear that all of the plurality of flexibly-acting working members 18 are supported by a respective support system. Therefore, the flap wheel 7 having the plurality of flexibly-acting working members 18 and their respective support systems 8, 9, is a highly compacted flap wheel 7 with a substantially continuous running surface. Such a highly compacted flap wheel 7 may have between 30 - 60 flaps in case of a wheel diameter of 100 mm, up to between 60 - 120 flaps in case of a wheel diameter of 150 mm. It will be clear that the support system 8, 9 has an identical or similar profiled surface as compared to the working members 18 at the peripheral side 14 to support the flap 10.

[0057] The support system will be described in connection with a single working member 10. The support system 8, 9 extends between adjacent flexibly-acting working members 10. The support system enables to maintain the shape of a working member 10 and thus improves accuracy of the contoured surface on the substrate. The support system contacts the at least one working member 10 in the direction of rotation of the flap wheel 7. The support system contacts the at least one working member 10 in the direction of rotation over substantially the entire surface of the working member 10 to avoid out of plane deformation of the working member as much as possible. The support system may either be fixedly attached to the working member 10, or only contact the working member. In any case, the support system defines a minimum spacing between adjacent working members 10.

[0058] The support system 8, 9 comprises a first layer 8 and a second layer 9. The first layer 8 comprises a non-woven material as best shown in figure 3. The second layer 9 is different and separate from the first layer 8. The second layer 9 comprises a foam material. The first 8 and second layer 9 are attached at opposite surfaces that extend radially. In this case, the first 8 and second layer 9 are attached in order to form a unity. The first 8 and second layer 9 are attached by adhesive bond, melt bond or any other suitable way of surface bond.

[0059] The nonwoven material of the first layer 8 is characterized by one or more of, a grit size between 130 and 170 mesh in particular about 150 mesh, a weight between 1400 and 1800 gram per square meter, in particular about 1600 gram per square meter. The foam material of the second layer 9 comprises one or more of silicon and polyurethane. Here, the foam material of the second layer 9 is characterized by a Shore A hardness of between 35 - 55.

[0060] The second layer 9 is different from the first layer 8 in that a density of the second layer is lower compared to a density of the first layer. More specifically, a ratio of the density of the second layer 9 and the density of the first layer 8 is between 0,3 and 0,6, in particular about 0,4.

[0061] The foam material of the second layer 9 is characterized by a weight between 500 and 800 gram per square meter, in particular about 660 gram per square meter.

[0062] The single working member 10 is different and separate from the first 8 and second layer 9. The working member 10 comprises a carrier which is usually a fabric that is either metalized or provided with a resin. The fabric with metal or resin functions as a matrix to position and hold the abrasives and this is known per se in connection with flaps of a flap wheel.

[0063] The support system 8, 9 comprises abrasives. The support system may comprise abrasives different from abrasives in the plurality of flexibly-acting working members 18.

[0064] The plurality of flexibly-acting working members 18 and / or the support system 8, 9 comprises electrically conductive material. The electrically conductive material of the plurality of flexibly-acting working members and / or the support system is in electrically conductive connection with at least the central hub 22.

[0065] The flap wheel 7 comprises a pair of opposite disk members 11 , 12. The disk members 11 , 12 contact with axial sides of the plurality of flexibly-acting working members 18. As a result, the disk members 11 , 12 support and enclose the working members 18 in an axial direction of the central hub 22. The disk members of the pair of opposite disk members may comprises a foam layer and a rubber layer (not shown). The disk members 11 , 12 overlaps as much as possible in a radial direction with the working members 18 in order to maximize support. In this case, the disk members 11 , 12, extends over about 95% of the length of the working member 18 in the radial direction of the flap wheel.

[0066] The central hub 22 in this case comprises a main body 19 and a closing member 20. The main body 19 is connectable to a rotary drive (not shown). The closing member 20 contacts the main body 19 in order to enclose the working members 18. In this case, the disk members 11 , 12 are integral with respectively the main body 19 and the closing member 20.

[0067] Figure 5 shows a further embodiment of a flap wheel 15 according to the invention in a perspective view. The flap wheel 15 has a central axis of rotation 17. Each working member 21 has an outer profiled surface 23 comprising at least a curved section 24 for substantially matching the contoured surface on the substrate. The flap wheel 15 of figure 5 is in effect half of the flap wheel 7 of figure 2.

[0068] Fig. 6 is a further embodiment of a flap wheel 7 according to the invention in a perspective view. Fig. 7 is a detail of the flap wheel 7 of fig. 6. In general, only differences are described with respect to the previous embodiment as shown in figures 2-4. As indicated, the support system 8, 9 may comprise abrasives. The support system comprising abrasives contributes to the abrasive action of the flap wheel 7. In this embodiment, the support system therefore comprises a support system working flap 25. The support system working flap 25 extends between a first layer 8 and a second layer 9 of the support system that supports the single working member 10. Here, each support system 8, 9 comprises a support system working flap 25.

[0069] Fig. 8 is a schematic drawing showing a detail of a working member (also “flap”) 25 as used in the embodiment of figures 6 and 7. The cross-sectional side view shows a basic construction of the working member 25. The working member comprises a backing material layer 26. This backing material layer 26 provides basic mechanical integrity to the working member 25. The working member 25 comprises a first layer of adhesive 27. The first layer of adhesive 27 is applied to the backing material layer 26 and holds the abrasive particles 30, also “abrasive grains”. The first layer of adhesive 27 is also referred to as "make coat" in the abrasives industry. The working member 25 comprises a securing layer 28 applied on top of the first layer of adhesive 27. The securing layer 28 is thus applied over the abrasive particles 30 to anchor them even more securely. The securing layer 28 is also referred to as "size coat" in the abrasives industry. Lastly, the working member 25 comprises a top coating layer 29. The top coating layer 29 is applied on top of the securing layer 28. The top coating layer 29 is also referred to as "super-size coat" in the abrasives industry. Such a top coating layer 29 may contain grinding aid materials to enhance performance during use of the working member.

[0070] During application of abrasive particles to the working member 25, abrasive particles can be aligned in order that all particles extend transverse with respect to working member 25. This reduces contact between a resin matrix that holds the abrasive particles and the surface of a workpiece to be treated. This in turn avoids build-up of heat and high surface temperature, and therefore operational lifetime of the working member 25 increases. This is even more important for flap wheels 7, as build up of heat will normally be a limiting factor to consider.

[0071] Alignment of abrasive particles can be done by making use of so called electrostatic coated abrasive, in particular diamond abrasive, in combination with application of an electric field during applying the abrasive particles to the working member 25. Such a process to align abrasive particles is known per se. The basic construction of the working member 25 has been described in connection with the support system working flap 25 of the embodiment shown in figures 6 and 7. It will however be clear that the single working member 10 that is supported by the support system 8, 9, can have a similar basic construction including the aligned abrasive particles.

[0072] The present invention has been described above with reference to a plurality of exemplary embodiments as shown in the drawings. Modifications and alternative implementations of some parts or elements are possible and are included in the scope of protection as defined in the appended claims.

[0073] -0-0-0-0-0- List of reference numbers

[0074] 1 Polishing wheel

[0075] 2 Central axis

[0076] 3 Curved surface

[0077] 4 Prior art flap wheel

[0078] 5 Central axis of rotation

[0079] 6 Flaps

[0080] 7 Flap wheel according to invention 8, 9 Support system

[0081] 8 First layer

[0082] 9 Second layer

[0083] 10 Single working member, also flap 11, 12 Pair of opposite disk members

[0084] 13 Central wheel axis of rotation

[0085] 14 Peripheral side

[0086] 15 Further embodiment of a flap wheel 16 Profiled surface

[0087] 17 Central axis of rotation

[0088] 18 Plurality of working members

[0089] 19 Main body of hub

[0090] 20 Hub closing member

[0091] 21 Working members

[0092] 22 Central hub

[0093] 23 Outer profiled surface

[0094] 24 Curved section

[0095] 25 Support system working flap

[0096] 26 Backing material layer

[0097] 27 First layer of adhesive

[0098] 28 Securing layer

[0099] 29 Top coating layer

[0100] 30 Abrasive particles

Claims

Claims1. Flap wheel (7) for abrading contoured surfaces on a substrate, the flap wheel comprising; - a central hub (22) defining a central wheel axis of rotation (13),- a plurality of flexibly-acting working members (18) being attached to the central hub and extending radially with respect to the central wheel axis of rotation for providing abrasive action on the substrate at a peripheral side (14) of the working members opposite the central hub, each working member having an outer profiled surface (16) comprising at least a curved section (24) for substantially matching the contoured surface on the substrate, wherein the flexibly-acting working members comprise abrasives comprising diamond or any other suitable super-abrasive material.

2. Flap wheel according to claim 1 , comprising subsequent flexibly-acting working members comprising different abrasives.

3. Flap wheel according to claim 1 or 2, comprising a support system (8, 9) for maintaining the shape of at least one of the plurality of flexibly-acting working members, wherein the support system extends between adjacent flexibly-acting working members.

4. Flap wheel according to claim 3, wherein the support system comprises a first layer (8) comprising a non-woven material.

5. Flap wheel according to claim 4, wherein the support system comprises a second layer (9) different and separate from the first layer and comprising a foam material.

6. Flap wheel according to claim 5, wherein the first and second layer are attached at opposite surfaces that extend radially in order to form a unity.

7. Flap wheel according to a preceding claim 4-6, wherein the nonwoven material of the first layer is characterized by one or more of, a grit size between 130 and 170 mesh in particular about 150 mesh, a weight between 1400 and 1800 gram per square meter, in particular about 1600 gram per square meter.

8. Flap wheel according to a preceding claim 5-7, wherein the foam material of the second layer comprises one or more of silicon and polyurethane, and the foam material of the second layer is characterized by a Shore A hardness of between 35 - 55.

9. Flap wheel according to a preceding claim 5-8, wherein the second layer is different from the first layer in that a density of the second layer is lower compared to a density of the first layer.

10. Flap wheel according to a preceding claim 5-9, wherein a ratio of the density of the second layer and the density of the first layer is between 0,3 and 0,6, in particular about 0,4.

11. Flap wheel according to a preceding claim 5-10, wherein the foam material of the second layer is characterized by a weight between 500 and 800 gram per square meter, in particular about 660 gram per square meter.

12. Flap wheel according to a preceding claim 3-11 , the support system comprising abrasives.

13. Flap wheel according to a preceding claim 3-12, wherein the support system comprises abrasives different from abrasives comprised in the plurality of flexibly-acting working members.

14. Flap wheel according to a preceding claim 3-13, wherein the plurality of flexibly-acting working members and / or the support system comprises electrically conductive material in electrically conductive connection with at least the central hub.

15. Flap wheel according to a preceding claim 3-14, wherein the support system comprises a pair of opposite disk members in contact with axial sides of the plurality of flexibly-acting working members in order to support and enclose the working member in an axial direction of the central hub, wherein a disk member of the pair of opposite disk members preferably comprises a foam layer and a rubber layer.-O-O-O-O-O-O-

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