Rotary abrasive brush for deburring and method of manufacturing

Abstract

A rotary tool containing a core hub with helical groove on its outer surface filled in with continuous abrasive filament formed by folding of a pre-cut abrasive sheet including multiple bristle like straps extending radially from the hub. The method of manufacturing includes the steps of providing a hub, and forming a helical groove with inverted V-shaped cross-section along its cylindrical surface. An abrasive element is wound around the hub so that the folded edge is fed in the V-grove and is buckled inside the groove providing, along with securing it by sufficient pre-tension of the abrasive element, a secure anchoring of the abrasive element through locking of the buckled edge. The abrasive filament is formed from a roll of abrasive cloth as one continuous piece using a cutting operation and is provided with center-line perforations. These perforations assist folding the filament by providing it with discrete and desired flexibility as well as weakening it in such way that it assists the process of folded edge buckling inside the groove during winding and therefore forms a tight anchoring junction with the hub without need for an adhesive.

Claims

1. An abrasive tool, comprising: a rotatable body having an outer surface and a helical groove formed within said outer surface, said helical groove having a bottom and an opening, said helical groove having an inverted v-shaped cross sectional profile wherein said bottom of said helical groove is wider than said opening of said helical groove; a continuous abrasive filament having a first end, a second end, a longitudinally oriented fold center line and a plurality of abrasive straps integral with said filament and extending outwardly from said fold center line of said filament, each of said plurality of abrasive straps defined from an adjacent one of said plurality of abrasive straps by at least a first slit extending outwardly from said fold center line of said filament, each said first slit having an end outwardly and laterally removed from said fold center line, said filament being positioned within said helical groove by a longitudinally oriented folded edge, said filament having a plurality of longitudinally extended perforations oriented longitudinally along said fold center line of said filament at a position on the fold center line which is separated from and corresponds to said first slit, and is adapted to assist folding of said filament along said fold center line thereby providing said longitudinally oriented folding edge along said fold center line, said plurality of perforations assisting buckling of said longitudinally oriented folding edge as said filament is wound over said rotatable body, the first end and the second end of said filament being secured with respect to said rotatable body.

2. The rotary tool as set forth in claim 1, wherein said body is composed of foam.

3. The rotary tool as set forth in claim 2, wherein said foam is polymeric foam.

4. The rotary tool as set forth in claim 3, wherein said foam is polystyrene.

5. The rotary tool as set forth in claim 1, wherein said abrasive filament comprises abrasive tape.

6. The rotary tool as set forth in claim 5, wherein said abrasive tape comprises cloth backed abrasive tape.

7. The rotary tool as set forth in claim 1, including separations between said straps provided in a shape assisting augmenting strength and reducing wear and tearing of said straps.

8. The rotary tool as set forth in claim 1, wherein said body comprises a hub.

9. The rotary tool as set forth in claim 8, wherein said hub is barrel shaped.

10. The rotary tool as set forth in claim 8, wherein said hub is cylindrical.

11. The rotary tool as set forth in claim 8, wherein said hub is conical.

12. The rotary tool as set forth in claim 1, wherein the perforations has a length and a width, the length extends in the longitudinal direction, and the length is greater than the width.

13. A method of manufacturing an abrasive tool, comprising: a) providing a rotatable body having an outer surface; b) providing a helical groove within said outer surface of said rotatable body, said helical groove having a bottom and an opening, said helical groove having a bottom and an opening, said helical groove having an inverted v-shaped cross sectional profile wherein said bottom of said helical groove is wider than said opening of said helical groove; c) providing a flexible length of abrasive material having a first end, a second end, a longitudinally oriented fold center line and a plurality of abrasive straps integral with said filament and extending outwardly from said fold center line of said filament, each of said plurality of abrasive straps defined from an adjacent one of said plurality of abrasive straps by at least a first slit extending outwardly from said fold center line of said filament, each said first slit having an end outwardly and laterally removed from said fold center line, said filament being positioned within said helical groove by a longitudinally oriented folded edge, said filament having a plurality of longitudinally extended perforations oriented longitudinally along said fold center line of said filament at a position on the fold center line which is separated from and corresponds to said first slit, and is adapted to assist folding of said filament along said fold center line thereby providing said longitudinally oriented folding edge along said fold center line, said plurality of perforations assisting buckling of said longitudinally oriented folding edge as said filament is wound over said rotatable body, the first end and the second end of said filament being secured with respect to said rotatable body; d) folding said flexible length of abrasive material centrally between said strap members along said fold center line; e) positioning said longitudinally oriented folding edge of said flexible length of abrasive material within said helical groove; and f) securing said longitudinally oriented folding edge of said flexible length of abrasive material within said helical groove on said body.

14. The method as set forth in claim 13, wherein said flexible length is produced by laser cutting or die cutting or water jet cutting of said abrasive material.

15. The method as set forth in claim 13, wherein said groove in said body is formed by cutting said body with a hot tool.

16. The method as set forth in claim 13, wherein said flexible length comprises tape.

17. The method as set forth in claim 16, wherein said tape comprises cloth backed tape.

18. The method as set forth in claim 13, wherein steps a) through e) are continuous.

19. The method as set forth in claim 13, wherein the perforations has a length and a width, the length extends in the longitudinal direction, and the length is greater than the width.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a general view of the hub (core) of the rotary brush made in a shape of a cylinder with a helical groove;

(2) FIG. 2 is a general view of the hub (core) of the rotary brush made in a shape of a cone with a helical groove;

(3) FIG. 3 is a general view of the hub (core) of the rotary brush made in a shape of a barrel with a helical groove;

(4) FIG. 4 shows one variant of the symmetrical foldable pattern of the precursor of the abrasive filament cut from a tape;

(5) FIG. 5 illustrates the process of winding of the folded filament around the drum;

(6) FIG. 6 is a cross-section of the drum with anchoring pins for the ends of the filament and with central bore for securing on the spindle;

(7) FIG. 7 is cross-section along line 7-7 of FIG. 6 of the spiral groove with folded filament in it and illustrating anchoring effect of the buckled edge of the folded line of the filament due to frictional/clamping forces;

(8) FIG. 8 illustrates in greater detail effect of buckling of the filament's folded edge;

(9) FIG. 9 provides greater details of the perforation assuring folding of the filament precursor and buckling of its edge;

(10) FIG. 10 is another variant of filament made from a non-folded abrasive precursor and having notches at the edge to be inserted and buckled inside the groove, and

(11) FIG. 11 illustrates the continuous process of manufacturing of the abrasive brush.

BEST MODE FOR CARRYING OUT THE INVENTION

(12) Referring initially to FIGS. 1 through 3, there is illustrated a variety of shapes for the brush cores 4, namely: cylindrical (FIG. 1), conical (FIG. 2) or barrel type (FIG. 3) with helical grooves 5 made on outer surfaces and bores 4 aligned with central rotational axes 6.

(13) End zones 19 of the grooves are used for anchoring the ends of the filament, generally denoted as plurality of extremities 9 with end radii 10 made by cutting abrasive tape 7 (FIG. 4) with slits 8, further described in the following figures.

(14) FIG. 5 schematically illustrates the general process of winding the filament 9 over drum 1 with the assistance of a feeding knife 17 aligned within fold line 12 (FIG. 4) of filament 9.

(15) Referring now to FIG. 6, pins 20, also presented in FIG. 11, are shown after insertion in drum 1 through the end part of filament 9 and generally perpendicular to its plane.

(16) FIG. 7 illustrates a cross-section of an inverted V-shape groove per FIG. 6 where folded edge 12 is buckled into a shape 13 also shown in greater detail in FIG. 8. Alternatively, a cord 18 can be used to reinforce the position of the filament 9 inside the groove 5.

(17) The theoretical width of buckled edge 12 is denoted by , which, as to mentioned above, is related to the ratio between radii R1 and R2 winding of filament 9 around drum 1. In essence, the depth of the groove 5 relative to the diameter of drum 1 and to the width a of the filament extremities 9 along with the width of the groove, define the end rate of buckling and level of clamping.

(18) Perforations 11 (FIGS. 8 and 9) or notches 14 (FIG. 10) provide intentional weakening of the filament edge 12 and assist in provoking the automatic buckling of the edge 12 inside the groove. These perforations can also be used in feeding and indexing during laser cut or other cutting processes.

(19) The manufacturing process (FIG. 11) can be continuous and includes feeding the abrasive tape 7 from a precursor roll 15, cutting or slicing to achieve desired pattern of filament(s) 9, removal of unused parts 16 of tape 7, folding along line 12 aligned with perforations 11, feeding into the groove 5 using knife 17 or other means and fixing the ends of filament 9 by pins 20 or other anchoring or securement means.

(20) One method of making drum 1 from foam material (example of which may be Polystyrene or Styrofoam of 2-6 lbs/ft^3 of density) is by using a hot wire. Slot 21, shown in FIG. 11 can be used for assisting such cutting and also can be used to secure drum 1 on the axle (not shown) necessary for winding and provide spring like effect to the drum 1 to equalize tension of the filament after winding. The final dimension of bore 4 can be assured by an additional finishing operations with conventional or specialized tools applicable for bore finishing in polymeric foams.

(21) Another desired method for making the inverted V-shape groove from the same material is by using a hot knife of an appropriate shape while the drum precursor is rotating with an axial feed rate generally equal to the pith of the helical groove. As mentioned above, all the operations can be done simultaneously or sequentially.

(22) Similar to the abrasive flap wheels known from the prior art, the tools of FIGS. 1 through 11 may be driven for rotation in either direction and since the abrasive material always has a higher coefficient of friction with the surface to be finished compared to the backing material, the filaments 9 are twisted and automatically face the working surface, providing high efficiency abrading and self-cleaning.