Abrasive brush

Abstract: This invention provides an abrasive brush having strength and abrasive characteristics similar or superior to those of conventional brushes, and which allows a brush assembly having a desired width dimension and a desired brush surface hardness to be readily and easily assembled. A disk-shaped abrasive brush (1) includes a radial inner hub (5) and a radial outer brush section (3), preferably the hub (5) being integrally formed with the brush section (3). The hub (5) is provided with a flat part, a recessed part (9, 11), and a projecting part (7). When two adjacent abrasive brushes are aligned adjacent to each other, the flat, recessed and projecting parts of the abrasive brushes are engaged with each other and define a pitch between the abrasive brushes.

Description: The present invention relates to an abrasive brush, and particularly to a roll-shaped laminated abrasive brush. Conventional laminated abrasive brushes made of nonwoven abrasive sheets compressed or packed on a shaft typically lack mechanical strength and often have a tendency to slip when the shaft is rotated. Attempts to eliminate these problems associated with such laminated abrasive brushes have been reported in Japanese Patent Publication Nos. (Kokai) 8-25229 and 9-201232. Kokai Publication 8-25229 discloses a holder for an abrasive disk tool. A plurality of disk-shaped sheet members, each composed solely of abrasive material, are aligned next to each other and secured, in a compressed state, to each other by snap-fit type fasteners. To optimize the axially compressed state and regulate the density of the abrasive material (disk-shaped sheet members), a separate spacer is placed or interposed between adjacent disk-shaped sheet members. Kokai Publication 9-201232 discloses an abrasive brush having disk-shaped sheet members composed of abrasive material that are aligned next to each other and compressed together to form a laminated roll brush with a jig, and then adhesive impregnated in the sheet members is cured to maintain a laminated roll shape. The laminated brush is mounted on a spindle of a rotating device via a center through-hole. The device reported in Kokia 8-25229 has a problem in that the dimensions (lengths) of the snap-fit type fasteners determine an overall width of the resultant brush. In addition, when a brush assembly of a highly compressed type is manufactured using intervening spacers, there is a further problem in that a specialized device or tool is necessary for the assembly of the brush, resulting in difficult assembly at a job site. US-A-3080637 relates to a device for modifying the surface characteristic of a fibrous material. The device is a napper cylinder comprising a shaft with a series of interlocking pointed napping discs mounted thereon. Each napping disc has a cylindrical hub portion with a circular opening formed therein to receive the shaft. The hub is formed on one surface thereof with male projections wherein the other surface of the hub is formed with female depressions for interlocking the discs and preventing relative rotation thereof. In order to manufacture the brush reported in Kokai Publication 9-201232, a large installation is required for curing the adhesive, which cure is unsuitable for being carried out at a job site, and therefore the assembly of this type of brush (assembly) is generally carried out in a specialized facility. Also, it may be difficult to obtain a desired brush surface hardness by the curing of the adhesive. It is the object of the present invention to provide an improved abrasive brush. This object is achieved with the subject-matter according to the claims. The present invention preferably provides a reasonable and economical abrasive brush having a strength and abrasive characteristic similar or superior to those of conventional brushes, and which allows a brush assembly having a desired width dimension and a desired brush surface hardness to be readily and easily manufactured. The present invention provides an abrasive brush assembly according to claim 1. It is preferred that the hub is formed through injection molding a predetermined plastic or resin, wherein at least an inner periphery of the brush section is formed from a material having numbers of openings, to permit molten resin for the injection molding of the hub to flow into the openings, and wherein the hub is integrally formed with the brush section, in such a manner that a radial inner portion of an abrasive material penetrates into an outer peripheral side surface of the hub, and that the molten resin for the injection molding of the hub flows into and is solidified within the openings of the penetrated radial inner portion of the brush section. The figures exemplify preferred embodiments in accordance with the present invention. Fig. 1 is a plan view of one face of an abrasive brush of the present invention. Figs. 2 (a-c) are cross-sectional views of the abrasive brush of Fig. 1 taken along section lines A-A, B-B, and C-C. Fig. 3 is a plan view of another face of the abrasive brush of Fig. 1. Figs. 4 (a-c) are illustrations of four abrasive brushes of the present invention. Fig. 5 is a plan view of one face of another abrasive brush of the present invention. Figs. 6 (a-c) are cross-sectional views of the abrasive brush of Fig. 5 taken along section lines A-A', B-B' and C-C'. Fig. 7 is a plan view of another face of the abrasive brush of Fig. 5. Preferred embodiments of the present invention will be described below with reference to the attached drawings. Figs. 1 to 4 illustrate a first embodiment of an abrasive brush 1. Figs. 5 to 7 illustrate a second embodiment of an abrasive brush 21. In Fig. 1, the abrasive brush 1 includes a radial outer brush section 3 of a doughnut-shaped plate and a radial hub 5 in a shape of a small disk. The brush section 3 is formed of a non-woven abrasive material made of polyester or polyamide fibers having a thickness, for example, in a range from 5 to 50 denier. The hub 5 is formed of a plastic or resin material such as ABS, polyamide, polyester or others, for example, by an injection molding process, but of course is not limited thereto, provided a predetermined strength and a proper bonding of the brush section to the hub is obtainable. The brush section 3 and the hub 5 are integrally coupled with each other by the adhesion obtained by the use of a predetermined adhesive or by a bonding force generated when a molten plastic or resin is solidified after flowing into fibrous interstices or voids in material of the brush section 3 during the injection molding of the hub 5. The brush section 3 (abrasive material) may be formed of any material other than the non-woven fabric provided it has the material interstices having a characteristic satisfying the above-mentioned requisites, such as a sand paper, a woven fabric or a grindstone (stone + adhesive). The hub 5 of the abrasive brush 1 has a basic thickness, for example, approximately equal to half of the thickness of the brush section 3 (radial outer abrasive material brush section) and is provided with a projecting part 7, a recessed part 9 and a through-hole part 11. That is, in each of two cross-sections A-A of the hub 5, a projecting part 7 (Fig. 2(a)) extending parallel to the axial direction is provided on one side of the hub. Namely, four projecting parts 7 are equi-distantly arranged at four positions on a predetermined diametrical circle on one side of the hub. Similarly, in each of two cross-sections B-B of the hub 5, a recess part 9 having a depth approximately equal to half of the projected height of the projecting part 7 is provided. That is, four recesses 9 are equi-distantly arranged at four positions on a predetermined diametrical circle on a side of the hub that has no projections 7 present. Also, similarly, in each of two cross-sections C-C of the hub 5, a through-hole part 11 of a shape complementary to that of the projecting part (i.e., smoothly engageable with the projecting part 7) is provided. That is, four through-hole parts 11 are equi-distantly arranged at four positions on a predetermined diametrical circle. An attachment hole 13 is provided in the center of the hub for mounting the brush onto a rotary shaft of a tool such as a grinder, not shown. An abrasive brush assembly of a wider width is assembled from a plurality of the abrasive brushes 1 of the above-mentioned structure. In one embodiment, as shown in Fig. 4(a), a predetermined number (five in Fig. 4(a)) of the abrasive brushes 1 are arranged so that the projecting part 7 (in the cross-section A-A) of the hub 5 of one abrasive brush 1 is brought into contact with a flat part (in the cross-section A-A) which is neither the recessed part 9 nor the through-hole part 11 of the hub 5 of the adjacent abrasive brush 1, whereby the abrasive brushes are coupled together at a pitch (equal pitch) defined by the engagement relationship between the hubs to form an abrasive brush assembly. According to this embodiment, the brush sections 3 (abrasive material) are minimally compressed to result in the abrasive brush assembly having the widest width. In a second embodiment, as shown in Fig. 4(b), a predetermined number of the abrasive brushes 1 are arranged so that the projecting part 7 (in the cross-section A-A) of the hub 5 of one abrasive brush 1 is inserted into the recessed part 9 (in the cross-section B-B) which is neither the through-hole part 11 nor the flat part of the hub 5 of the adjacent abrasive brush 1, whereby the abrasive brushes are coupled together at a pitch (equal pitch) defined by the engagement relationship between the hubs to form an abrasive brush assembly. According to this embodiment, the brush sections 3 (abrasive material) are more compressed compared to Fig. 4(a) to result in the abrasive brush assembly with a width narrower by a predetermined amount than in the embodiment of Fig. 4(a). In a third embodiment, as shown in Fig. 4(c), a predetermined number of the abrasive brushes 1 are arranged so that the projecting part 7 (in the cross-section A-A) of the hub 5 of one abrasive brush 1 is inserted into the through-hole part 1 (in the cross-section C-C) which is neither the recessed part 9 nor the flat part of the hub 5 of the adjacent abrasive brush 1 (so that the flat portions of the adjacent hubs are brought in contact with each other), whereby the abrasive brushes are coupled together at a pitch (equal pitch) defined by the engagement relationship between the hubs to form an abrasive brush assembly with a width narrower than the brush assembly illustrated in Fig. 4(b). The present invention should not be limited to the above three embodiments, but includes various abrasive brush assemblies with different widths, and also having different brush surface hardness, by variously combining the projecting, recessed and through-hole parts of the assembly hubs. It is also possible to form various abrasive brush assemblies with different overall width dimensions by providing in the hub 5 of the abrasive brush 1 a so-called concave (the recessed part 9 and the through-hole 11) and a so-called convex (the projecting part 7) and differentiating the engagement relationship between the concave and the convex when the abrasive brushes are adjacent to each other to form the brush assembly. By changing the overall width dimension of the brush sections, the compressive degree of the abrasive material, i.e., the brush surface hardness is also variable. Since the hub provided in a central region (radial inner region) which ought to be required for a high compressive force in the prior art is formed of a solid member (which is not required to be compressed, in other words, which could be considered to have been compressed in advance to a predetermined dimension) and a portion necessary for being compressed during the process for superposing the abrasive brushes with each other is limited to the abrasive material section (radial outer region), a high compressive force (or installation) becomes unnecessary unlike the prior art. Thus, the customer at a job site can readily and quickly assemble a desired abrasive brush assembly. An alternative abrasive brush of the present invention is described with reference to Figs. 5 to 7 wherein parts and portions common to those of the brush illustrated in Figs. 1-4 are denoted by the same reference numerals. An abrasive brush 21 includes a brush section 3 and a hub 25. The hub 25 has a basic thickness, for example, approximately equal to half a thickness of the brush section 3 (radial outer abrasive material section) and is provided with a projecting part, recessed part and through-hole part. That is, in two cross-sections A-A' of the hub 25, a projecting part 27a extending parallel to the axial direction is provided on one side of the hub. On the other side of the radial inner section relative to the projecting part 27a, a recessed part 29a is provided, and a through-hole part 31 a is provided in a further radial inner section, wherein the recessed part 29a is continuous to the through-hole part 31a. The projecting part 27a, the recessed part 29a and the through-hole part 31a are equi-distantly arranged at four positions on a predetermined diametrical circle on the one or other sides of the hub. Similarly, in two cross-sections B-B' of the hub 25, a recessed part 29b is provided on one side, and a through-hole part 31b is provided in a further radial inner section, wherein the recessed part 29b is continuous to the through-hole part 31b. On the other side, a projecting part 27b extending parallel to the axial direction is provided in another radial inner section. The recessed part 29b, the through-hole 31b and the projecting part 27b are equi-distantly arranged at four positions on a predetermined diametrical circle. Similarly, in two cross-sections C-C' of the hub 25, a through-hole part 31c is provided and a projecting part 27c is provided on one side of a further inner section, while a recessed part 29c is provided on the other side of a the inner section. The recessed part 29c, the through-hole part 31c and the projecting part 27c are equi-distantly arranged at four positions on a predetermined diametrical circle. Each of the projecting parts 27a to 27c of the hub 25 have an approximately equal projected height and each of the recessed parts 29a to 29c has a depth approximately equal to half a projected height. If a plurality of the abrasive brushes of the embodiment of Figs. 5-7 are arranged adjacent to each other, it is possible to obtain various abrasive brush assemblies having different width dimensions as well as brush surface hardness in accordance with manner of assembly similar to those already described with reference to the embodiment of Figs. 1-4. Dimensions of the concave (the recessed part and the through-hole) and the convex features (the projecting part) may be individually determined in consideration of the strength of material constituting the hub or the magnitude of torque applied on the brush when used. Since the structure is such that the brush pitch is defined when the projecting part is in contact with the bottom of the recessed part, it is favorable that the concave/convex engagement is made with sufficient mutual clearance; particularly, the projecting part is preferably, for example, of a trapezoidal cross-sectional shape so that it is easily engageable with and/or guided into the mating recess part. While the concave or the convex features are equi-distantly arranged at four positions on a predetermined diametrical circle in either of both the above-mentioned embodiments, the present invention should not be limited to only those embodiments. Unless a rotational balance becomes unstable, these features may be equi-distantly arranged optionally at N positions (N ≥ 3). The through-hole provided at a center of the hub mainly serves for mounting the abrasive brush assembly on a rotary shaft, but may be used for the relative positioning and alignment of the brushes when they are superposed (assembled) with each other, or if necessary, another through-hole may be separately provided for this purpose. Any material may be used for forming the hub provided it has suitable processability, including materials such as plastics or resins, metal and wood. Plastics or resins are preferred because they are processable using molding methods, dimensional, stable, and lightweight. A flange may be attached to each of opposite sides of the brush to reduce a (so-called) blooming phenomenon of an outer peripheral edge of the brush. The above-mentioned two embodiments are those typically applied to an abrasive brush assembly used for a large-sized grinder. The present invention, however, should not be limited to the application to such a large-sized device, but may be applied, for example, to a hand-held type grinder (a so-called straight grinder) not shown. That is, if the abrasive brush of the hand-held tool has the structure disclosed in the above-mentioned embodiments, it is possible to readily and quickly construct the abrasive brush assembly on site. Also, it is possible to obtain various brushes having different width dimensions by the simple angular positioning of adjacent hubs. According to the present invention, a brush assembly having a desired width dimension and therefore a desired brush surface hardness can be extremely quickly, readily and simply constructed to provide a reasonable and economical abrasive brush.

Claims: An abrasive brush assembly comprising abrasive brushes, wherein an abrasive brush including a radial inner hub and a radial brush section, the hub being integrally formed with the brush section, and the hub comprises two faces having a flat part, a recessed part and a projecting part, wherein the faces of adjacent brushes are adapted to engage with each other, characterized in that the projecting part of the hub of one abrasive brush is engaged respectively with the flat, recessed and projecting parts of an adjacent hub of a second abrasive brush to respectively define mutually different pitches between the abrasive brushes. The assembly of claim 1 , wherein the hub and brush sections of a brush are made of an injection molded plastic or resin.

Inventors: NAGAFUCHI NAOHIRO, NAGAFUCHI, NAOHIRO
Applicants: MINNESOTA MINING & MFG, MINNESOTA MINING AND MANUFACTURING COMPANY
Application year: 2000
Main classification: B24D13
IPC codes: B24D13