US20110021117A1

US20110021117A1 - Lightweight flap wheel

Info

Publication number: US20110021117A1
Application number: US12/839,823
Authority: US
Inventors: Douglas M. Bullock; Andrew Cross
Original assignee: Unisand Inc
Current assignee: Unisand Inc
Priority date: 2009-07-21
Filing date: 2010-07-20
Publication date: 2011-01-27

Abstract

A rotary finishing device is provided comprising a substantially solid hub having an inner periphery and an outer periphery, the inner periphery defining an axial throughhole. The device further provides a plurality of slots formed about the outer periphery of a generally circular hub, each of the plurality of slots being defined by a pair of side portions extending from the outer periphery. Each of the pair of side portions includes a tip portion, an intermediate side surface portion, and a base portion. The slot increases in width from the outer periphery to the base portion. A finishing media is secured in each of the plurality of slots by an epoxy resin, wherein each of the slots is consumed in its entirety by a combination of mounting ends of the finishing media and the epoxy resin. The hub and the consumed slots form a solid integral finishing device extending from the inner periphery to the outer periphery.

Description

The present invention claims priority to U.S. Provisional Patent Application Ser. No. 61/227,113 filed Jul. 21, 2009.

BACKGROUND

The present disclosure relates generally to a rotary finishing device, and more particularly to a flap-type or flap wheel rotary finishing device.
Rotary finishing tools typically include pieces, strips, or sections of a finishing medium (i.e. abrasive material) attached thereto. Such tools have proven to be very effective in the finishing of a wide variety of components such as those made from metal or the like. One such exemplary rotary finishing tool utilizes generally rectangular pieces of abrasive cloth, paper, or other non-woven material (such as sandpaper), to provide a rotary abrasive device.
One of the more common rotary finishing tools or devices is known in the art as a flap wheel. These flap wheels typically have annular arrays of flexible finishing strips and are commonly used in the finishing art. Most conventional rotary finishing devices consist of flexible strips each comprising sheets of material for finishing a surface of a piece. Many of these rotary finishing devices have abrasive particles bonded on one face thereof. Such rotary abrasive devices are useful for contoured polishing, cutting, or surface abrading of a variety of metal surfaces.
Various fabrication methods for such a rotary device are known. One such conventional method requires that the finishing sheets have two notches in their opposite side edges near the base end of each strip. As the strips are arranged in an annular array, the notches form concentric circular depressions on opposite sides of the annular array. Suitable circular reinforcement mechanisms, such as two metallic end caps are mounted on opposite sides of the array. Each end cap has an inwardly extending lip, which engages the circular depressions to mechanically grip the inner ends of the finishing strips. This method thus relies on the mechanical interference created between the two metallic end caps to maintain the base ends of the strips to remain in contact with a hub of the rotary device. Although a rotary finishing device of this configuration performs suitably, its manufacture is rather expensive and requires two notches to be formed in each strip prior to assembly. The forming of these notches is both time consuming and costly. Further, the notches must be aligned properly with respect to each other to receive accurate placement of the metal end caps.
Another known fabrication method for a rotary finishing device involves attaching the strips to a metallic clip, such as by stapling. The metal clip with the attached strips is then loaded into a metal hub. A plurality of pins is then used to secure the hub to an end cap. These pins maintain the strips in communication with the metal hub, such that it is relatively difficult for the strips to become disengaged from the hub during polishing. However, these rotary devices are also relatively expensive and also require a relatively cumbersome assembly process.
Therefore, a need exists for a rotary finishing device that is relatively inexpensive and easy to manufacture, but has sufficient strength, durability, and trueness to withstand the high operating speeds to which these devices are subjected.

SUMMARY

One aspect of the present disclosure is to provide a rotary finishing device that has abrasive flaps attached to the wheel's hub in slots that, due in part to geometric design, increase holding strength proportionate to the centrifugal forces imparted.
Another aspect of the present disclosure is to provide a rotary finishing device that is less expensive than prior rotary finishing devices.
Another aspect of the present disclosure is to provide a rotary finishing device that decreases the assembly time of the device without compromising its strength or integrity.
Yet another aspect of the present disclosure is to provide a rotary finishing device that can be inexpensively manufactured for a wide variety of different applications.
A further aspect of the present disclosure is to provide a rotary finishing device that can be manufactured in a variety of different widths and diameters.
Still another aspect of the present disclosure is to provide a rotary finishing device that decreases the associated machine time and wear on the rotating mechanism.
Still yet other objects of the present disclosure are to provide a rotary finishing device that provides for quieter rotation, more balance, less weight, and truer spinning.
In one exemplary arrangement, a rotary finishing device is provided comprising a substantially solid hub having an inner periphery and an outer periphery, the inner periphery defining an axial throughhole, wherein the axial throughhole defines a passage way for mounting onto an axle for driving the rotary finishing device. The device further provides a plurality of slots formed about the outer periphery of a generally circular hub, each of the plurality of slots being defined by a pair of side portions extending from the outer periphery. Each of the pair of side portions includes a tip portion, an intermediate side surface portion, and a base portion. The slots are proximal to the outer periphery and distal to the inner periphery. Each of the tip portions has a generally flat apex. At least a portion of each of the side surface portions is further defined as straight. The slot increases in width from the outer periphery to the base portion. A finishing media is secured in each of the plurality of slots by an epoxy resin, wherein each of the slots is consumed in its entirety by a combination of mounting ends of the finishing media and the epoxy resin. The hub and the consumed slots form a solid integral finishing device extending from the inner periphery to the outer periphery.
In another exemplary arrangement, a rotary finishing device is provided comprising a substantially solid hub having an inner periphery and an outer periphery, the inner periphery defining an axial throughhole, wherein the axial throughhole defines a passage way for mounting onto an axle for driving the rotary finishing device. The device further provides a plurality of slots formed about the outer periphery of a generally circular hub, each of the plurality of slots being defined by a pair of side portions extending from the outer periphery. Each of the pair of side portions includes a tip portion, an intermediate side surface portion, and a base portion. The slots are proximal to the outer periphery and distal to the inner periphery. At least a portion of each of the side surface portions is further defined as straight. The slot increases in width from the outer periphery to the base portion. A finishing media is secured in each of the plurality of slots by an epoxy resin, wherein each of the slots is consumed in its entirety by a combination of mounting ends of the finishing media and the epoxy resin. A plurality of mounting lugs are formed through the hub to facilitate mounting and driving of the rotary finishing device, wherein the mounting lugs are positioned offset from a center of the hub. Under centrifugal load each of the slots exerts forces to an adjacent slot to increase securement of the finishing media in each of the slots. The plurality of slots is generally uniformly spaced around the generally circular hub. The hub and the consumed slots form a solid integral finishing device extending from the inner periphery to the outer periphery.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a flap wheel;

FIG. 2 is a front view of a flap wheel as shown in FIG. 1, in accordance with one embodiment of the present disclosure;

FIG. 3 is a rear view of the flap wheel shown in FIG. 1;

FIG. 4 is a side elevation view of the flap wheel shown in FIG. 1;

FIG. 5 is an enlarged partial front view of a hub of the flap wheel shown in FIG. 1;

FIG. 6 is an enlarged partial rear view of the hub of the flap wheel shown in FIG. 1;

FIG. 7 is a perspective view of a flap wheel hub, in accordance with a second embodiment of the present disclosure;

FIG. 8 is a front view of the flap wheel hub, in accordance with the second embodiment of the present disclosure;

FIG. 9 is a front view of a flap wheel hub, in accordance with a third embodiment of the present disclosure;

FIG. 10 is an enlarged view of one variety of a slot around the hub periphery; and,

FIG. 11 is an enlarged view of another variety of a slot around the hub periphery.

DETAILED DESCRIPTION OF THE DISCLOSURE

In accordance with the above and the other aspects of the present disclosure, a rotary finishing device 10 is provided. The rotary finishing device 10, to be described in more detail hereinafter, includes a generally disk-like or substantially solid hub 18 having an inner periphery 20 and an outer periphery 22. The inner periphery 20 defines a passageway or arbor hole 21 therethrough, including an axis of rotation 30. The outer periphery 22 of the hub 18 has a plurality of slots 12 extending therefrom. Each of the plurality of slots 12 is defined by a pair of side portions 13, 15 and a base portion 17. Additionally, the plurality of slots 12 are generally uniformly spaced around the outer periphery 22. Each of the plurality of slots 12 includes finishing media 14 securable therein.
The finishing device or flap wheel 10, in accordance with the present disclosure, provides a lightweight, balanced, inexpensive finishing device. The flap wheel 10 provides ease of changing wheel dimensions to accommodate various demands. The balanced and lightweight flap wheel 10 reduces stress on the machine it is mounted on due to reduced weight, reduced rotational inertia, and improved trueness. A series of mounting holes, keyholes, or slots 12 are provided wherein the slots 12 can use an epoxy resin 23 therein to hold finishing strips 14 in place and create a centrifugal locking force when the wheel is in rotation. The solid core hub 18 design enables ease of machining and eliminates the need for reduction flanges.
The wheel core or hub 18 can be made from various materials. The hub 18 can include a relatively lightweight material selected from one or more of the group consisting of polymer, PVC, acrylic, polycarbonate, ABS, nylon, delrin, phenolic resin, polyester, or similar.
Referring to FIGS. 1 through 6, one embodiment of the rotary finishing device 10 in accordance with the present disclosure is therein illustrated. The rotary finishing device 10 includes a generally solid circular hub 18 extending from the inner periphery 20 to the outer periphery 22. The inner periphery 20 defines a passageway, throughway, or arbor hole 21 that can be open to either side of the device. A variety of processes can be utilized to form the circular hub 18, such as injection moulding or machining. The hubs 18 can be formed with a variety of different diameters, widths, lengths and other configurations.
The outer periphery 22 of the device includes the plurality of slots 12 formed thereabout. In this embodiment, the slots 12 are defined by a pair of side portions 13, 15 that extend generally from the outer periphery inward. It will be understood that the side portions 13, of each of the slots 12 can form a variety of geometrical formations, including a widening of the slots 12 as the slots 12 extend toward the inner periphery 20.
As shown, each of the slots 12 includes a finishing media 14 disposed therein. The finishing media 14 may be comprised of a single sheet of material or a plurality of sheets of material. The finishing media 14 is intended to contact a surface to be finished. The finishing media 14 is disposed between a pair of side portions and its innermost portion 34 is located within the hub 18 proximal to the outer periphery 22. In one embodiment, the finishing media 14 is secured within each of the slots 12 by an adhesive, such as an epoxy 23. The epoxy 23 can be placed into the slots 12 whereby all space within the slot 12 is consumed by the epoxy 23 and the mounting ends 34 of the finishing media 14. The adhesive 23 is utilized to secure the finishing media 14 within each slot 12. It is to be appreciated that the finishing media 14 can be secured within each of the slots 12 in a variety of suitable manners, for example, secured via an epoxy resin, wherein each of the slots 12 is consumed in its entirety by a combination of mounting ends of the finishing media and the epoxy resin, thereby forming an integral hub component 18 extending from the inner periphery 20 to the outer periphery 22. In accordance with one arrangement of the present disclosure, the outer periphery 22 of the hub 18 and the opposing surfaces of each of the side portions 13, 15 can be subjected to a surface treatment prior to attachment of the finishing media within each slot. The surface treatment roughs up, abrades, heats, retreats, or otherwise prepares the contact surface to assist in adhering the finishing media to the hub. It will be understood that all or fewer than all of the contact surfaces may be subjected to the surface treatment. The surface treatment can also include etching, sand blasting, vibratory finishing, and a surface finish. It will be understood that other suitable surface treatments or surface finishing may be utilized.
A method for producing flap wheels 10 according to the disclosure includes producing abrasive sanding or polishing wheels using a polymer core or hub 18 with an inserted circumferential array of abrasive material sections 14. The polymer core or hub 18 can be machined, formed, or moulded with a pre-determined number of geometric slots 12 about its circumference or outer periphery 22. Sections of abrasive materials 14 of predetermined width are then inserted into the slots 12. It is to be appreciated that the width of the abrasive strips 14 can be the same as the thickness of the hub (FIG. 4). The abrasive sections 14 can be held in the slots 12 with a thermal set or thermoplastic 23 in a liquid state injected into the unfilled area of the slot 12. The resulting mounting arrangement results in an integrally formed hub 18 and flap device without any flanges, gaps or separate mounts. The locking or containment of the abrasive sections 14 under centrifugal loading is achieved by the slot 12 having a geometric shape which can be larger proximal to the base 17, relative to the slot opening along the outer circumferential surface 22. Under centrifugal load each slot 12 can also exert forces due to its geometric shape to the adjacent slot.
As described above, the slots 12 that hold the abrasive sections 14 can comprise a continuous array around the outer periphery 22. The widths of these slots 12 can be narrower (w1) at the outer periphery 22 and enlarge dimensionally (w2) as the slot 12 projects inward toward the base 17. A center line of each slot can be aligned with the center 30 of the flap wheel 10.
Exemplary slot counts (i.e. number of slots) can be in any of a variety of counts (refer to FIGS. 1 and 7-9). The number of slots, and the associated abrasive sections held therein, are determined by the application and the material being sanded. The slot counts can include an even number of slots in order to maintain balance while the flap wheel is spinning. It is to be appreciated that the number of slots can be an odd number, wherein the slots are equally spaced around the periphery of the hub.
Referring now to FIGS. 7-8, it is to be appreciated that hubs 118 of the flap wheels 110 can be of any size. Namely, the hubs 118 can be provided in a number of different diameters and/or thicknesses. In one exemplary embodiment the hub 118 can include dimensions of one inch thickness and nine inch outside diameter. It is to be appreciated that the hubs 118 can comprise any number of spaced through holes or slots (i.e. 15, 28, 39, 44, 48, etc.). FIGS. 7-8 display a flap wheel 110 having 28 slots 112. The width of the slot 112 openings can be varied as well and can change in width, for example, the width (w3) of the slot 112 at the outer periphery relative to the width (w4) of the slot 112 proximal to the base 117.
Additionally, the circular hubs have a centerline or reference line, which corresponds to the axis of rotation of the device. The reference line 40 exists that extends from the center point to a point between a pair of side portions. When the reference line 40 continues outwardly it passes between each of the side portions. At least a portion of the side surfaces can lie generally parallel to the reference line 40. This provides side portions that are oriented generally perpendicular to the outer periphery of the hub.
It is to be appreciated that the moment of inertia of an object about a given axis describes how difficult it is to change its angular motion about that axis. Therefore, it encompasses not just how much mass the object has overall, but how far each bit of mass is from the axis. The farther out the object's mass is, the more rotational inertia the object has, and the more force is required to change its rotation rate. For example, consider two hoops, A and B, made of the same material and of equal mass. Hoop A is larger in diameter but thinner than B. It requires more effort to accelerate hoop A (change its angular velocity) because its mass is distributed farther from its axis of rotation: mass that is farther out from that axis must, for a given angular velocity, move more quickly than mass closer in. So in this case, hoop A has a larger moment of inertia than hoop B.
As described in the present disclosure, the integral solid hub and mounting slots places more of its mass closer to the axis of rotation, when compared to a hoop-like hub, which reduces the rotational inertia of the hub and slots and thereby reduces the force required to change the rotation rate of the rotary finishing device.
Based on dimensional analysis alone, the moment of inertia (I) of a non-point object takes on the following form:
I=c·M·L ²

- where M is the mass; L is a length dimension taken from the centre of mass (in some cases, the length of the object is used instead); and, c is a dimensionless constant called the inertial constant that varies with the object in consideration.

Inertial constants are used to account for the differences in the placement of the mass from the center of rotation. Examples include:
c=1, thin ring or thin-walled cylinder around its center;
c=⅖, solid sphere around its center; and,
c=½, solid cylinder or disk around its center.
Therefore, the moment of inertia of a solid hub (i.e. as described in the present disclosure) is on the order of one-half the moment of inertia of a hoop-like hub if both are of the same mass and radius. In addition, because the hub and slots of the present disclosure are a solid integral component, the moment of inertia can be found by a single calculation and not by summing individual moments of inertia of several constituent parts.
Through holes or mounting lugs can be machined, formed, or drilled through the hub to facilitate mounting and driving of the flap wheel. In one arrangement, two through holes 46 are provided and spaced 180° from each other (FIGS. 1-8). In another alternative arrangement of a hub 218, four through holes 246 are provided and are located in positions at 0, 90°, 180°, and 270° (FIG. 9). The through holes 246 can be located off of the hub center or arbor hole 221. FIG. 9 displays a flap wheel 210 having 44 slots 212.
The flap wheels 10, 110, 210, as described above, operate with little or no vibrations through a variety of RPM ranges in the order of 500-3000 RPM's. The radial density of the hubs are uniform to enhance the performance and wear of the flap wheel. As described above, the abrasive sections flap sections can be glued, epoxied, or retained in their respective slots in order to remain intact eliminating gas therein and to hold the sandpaper sections in place through at least 3000 RPM's.
Alternative geometries for slots are shown in FIGS. 10 and 11. Each side portion of the slot can include a tip portion, a base portion, and a side surface extending between the base portion and the tip portion, and thereby provide alternative embodiments of the slot geometries 312, 412. Namely, FIG. 10 provides a rectilinear slot 312 that can be narrower at the opening of the slot and widen therefrom (i.e. tapered side walls 313, 315) as the slot 312 projects inward. FIG. 11 provides a rounded or bulbous inner section of the slot 412 that can be narrower at its opening wherein the side walls 413, 415 extend in a linear arrangement and then transition into a broader or wider opening (i.e. bulbous side walls) at the interior of the slot 412. In the embodiment shown in FIG. 11, the linear extension 417 of side walls 413, 415 is relatively shorter than the extension 419 of the larger rounded or arcuate shape at the base of the slot 412.
Referring again to FIGS. 1-11, various embodiments of the rotary finishing devices 10, 110, 210 in accordance with the present disclosure are therein illustrated. The rotary finishing devices can be utilized to finish a surface, such as by polishing, abrading, sanding, or the like. However, it will be understood that the finishing devices disclosed herein can be utilized for a variety of different purposes and can be formed with a variety of different configurations. Moreover, the finishing media utilized with the disclosed finishing devices can also vary depending upon the application for which the finishing devices will be used and can include cloth, sandpaper, non-woven media, or the like, and/or combinations thereof. It will also be understood that a variety of different finishing media may be utilized.
The material and construction of the aforementioned flap wheel allows the flap wheel to run quieter, smoother, and truer. The hub, according to the present disclosure, weighs less than comparable metal hubs and requires less energy to rotate. The hub has more balance, less moving parts, and is less expensive to manufacture.
While particular embodiments of the disclosure have been shown and described, numerous variations and alternate embodiments will occur to those skilled in the art. Accordingly, it is intended that the disclosure be limited only in terms of the appended claims.

Claims

1. A rotary finishing device, comprising:

a substantially solid hub having an inner periphery and an outer periphery, said inner periphery defining an axial throughhole;

said axial throughhole defines a passage way for mounting onto an axle for driving said rotary finishing device;

a plurality of slots formed about said outer periphery of a generally circular said hub, each of said plurality of slots being defined by a pair of side portions extending from said outer periphery;

each of said pair of side portions including a tip portion, an intermediate side surface portion, and a base portion;

wherein said slots are proximal to said outer periphery and distal to said inner periphery;

wherein each of said tip portions has a generally flat apex;

at least a portion of each of said side surface portions are further defined as straight;

said slot increases in width from said outer periphery to said base portion;

a finishing media secured in each of said plurality of slots by an epoxy resin, wherein each of said slots is consumed in its entirety by a combination of mounting ends of the finishing media and said epoxy resin; and,

said hub and said consumed slots forming a solid integral finishing device extending from said inner periphery to said outer periphery.

2. The rotary finishing device of claim 1, wherein said generally circular hub is a solid core hub.

3. The rotary finishing device of claim 2, wherein said solid core hub is formed of a material selected from the group consisting of polymer, PVC, acrylic, polycarbonate, and ABS.

4. The rotary finishing device of claim 2, wherein said solid core hub is formed of a material selected from the group consisting of nylon, delrin, phenolic resin, and polyester.

5. The rotary finishing device of claim 3, wherein said hub is formed by an extrusion process.

6. The rotary finishing device of claim 4, wherein said hub is formed by an extrusion process.

7. The rotary finishing device of claim 1, wherein at least a portion of each of said plurality of slots are subjected to a surface heat treatment process to assist in bonding said finishing media and said epoxy resin to said generally circular hub.

8. A rotary finishing device comprising:

said slot increases in width from said outer periphery to said base portion;

a finishing media secured in each of said plurality of slots by an epoxy resin, wherein each of said slots is consumed in its entirety by a combination of mounting ends of the finishing media and the epoxy resin;

a plurality of mounting lugs are formed through the hub to facilitate mounting and driving of the rotary finishing device, wherein said mounting lugs are positioned offset from a center of said hub;

under centrifugal load each of said slots exerts forces to an adjacent said slot to increase securement of said finishing media in each of said slots;

said plurality of slots being generally uniformly spaced around said generally circular hub; and,

9. The rotary finishing device of claim 8, wherein each of said tip portions has a generally flat apex.

10. The rotary finishing device of claim 8, wherein said generally circular hub is formed of a material selected from the group consisting of polymer, PVC, acrylic, polycarbonate, and ABS.

11. The rotary finishing device of claim 8, wherein said generally circular hub is formed of a material selected from the group consisting of nylon, delrin, phenolic resin, and polyester.

12. The rotary finishing device of claim 10, wherein said generally cylindrical hub is formed by an extrusion process.

13. The rotary finishing device of claim 11, wherein said generally cylindrical hub is formed by an extrusion process.

14. The rotary finishing device of claim 10, wherein said generally circular hub is formed by moulding.

15. The rotary finishing device of claim 11, wherein said generally circular hub is fowled by moulding.

16. The rotary finishing device of claim 8, wherein at least a portion of each of said plurality of slots are subjected to a surface heat treatment process to assist in bonding said finishing media and said epoxy resin to said generally circular hub.

17. A rotary finishing device comprising:

said axial throughhole defines a passage way for mounting onto an axle;

said slot increases in width from said outer periphery to said base portion;

a finishing media secured in each of said plurality of slots by an adhesive, wherein each of said slots is consumed in its entirety by a combination of mounting ends of the finishing media and the adhesive;

said plurality of slots being generally uniformly spaced around said generally circular hub;

said hub and said consumed slots forming a solid integral finishing device extending from said inner periphery to said outer periphery thereby reducing a moment of inertia of said hub; and,

wherein said generally circular hub is formed of a material selected from the group consisting of nylon, delrin, phenolic resin, and polyester.

18. The rotary finishing device of claim 17, wherein said moment of inertia of said hub is about one-half the moment of inertia of a hoop-like hub having substantially the same mass and radius of said hub.

19. The rotary finishing device of claim 17, wherein said generally cylindrical hub is formed by an extrusion process.

20. The rotary finishing device of claim 17, wherein said generally circular hub is formed by moulding.