Abrasive tool making process – material – or composition – With synthetic resin
Reexamination Certificate
2000-06-28
2002-07-02
Marcheschi, Michael (Department: 1755)
Abrasive tool making process, material, or composition
With synthetic resin
C051S307000, C051S309000, C051S293000, C051S308000, C451S527000, C451S533000
Reexamination Certificate
active
06413287
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an abrasive article, such as an abrasive brush, including a binder and a plurality of abrasive particles and a method of making such an abrasive article by reaction injection molding.
BACKGROUND OF THE INVENTION
Brushes have been used for many years to polish, clean and abrade a wide variety of substrates. These brush products typically have a plurality of bristles that contact the substrate. Abrasive particles can be added to bristles to increase their abrasiveness. There are many manufacturing steps necessary to manufacture a conventional abrasive brush having bristles which contain abrasive particles. A mixture of abrasive particles and a thermoplastic binder may be combined and then extruded to form a bristle. The bristle is then cut to the desired length. A plurality of these bristles are then mechanically combined to form a brush segment. Next, a plurality of these brush segments may be installed on a hub or plate to form a brush.
One example of such a brush is disclosed in U.S. Pat. No. 5,045,091 (Abrahamson et al.). In Abrahamson et al., a plurality of abrasive bristles are mechanically clamped together and a root system is installed to form a brush segment. A plurality of these brush segments are installed on a rotary hub. Another arrangement for mechanically mounting bristles on a hub to form a brush segment is disclosed in U.S. Pat. No. 5,233,719 (Young et al.). Young et al. teach a brush segment comprising a substrate with a carpet of bristles mounted on one side of the substrate, by means of a polymeric resin for example, and a root system extending from the opposite side of the substrate for engagement with a rotary hub. U.S. Pat. No. 5,400,458 (Rambosek) teaches a brush segment having a plurality of bristles embedded in a polymeric base portion. A root means for attaching the segment to a hub can be integrally molded with the base.
U.S. Pat. No. 5,233,794 (Kikutani et al.) discloses a rotary tool having a rotating tip formed integrally with a shaft. The rotary tool is formed of a thermosetting resin containing inorganic long fibers with a high degree of hardness as an abrasive means in an amount from 50% to 81% by volume. The long inorganic fibers can have a diameter in the range of 3 &mgr;m to 30 &mgr;m. In one of the embodiments of Kikutani et al., the rotating tip is formed as a column or cylinder with elements which correspond to the bristle of a brush extending from the tip.
U.S. Pat. Nos. 5,152,917 and 5,304,223 (Pieper et al.) teach coated abrasive articles comprising precisely shaped abrasive composites bonded to a backing. The abrasive composites comprise binder and abrasive particles. The precisely shaped composites can be in the form of, for example, pyramids, sawtooth grooves, or linear grooves. The maximum distance between corresponding points on adjacent composite shapes can be less than one millimeter. The coated abrasive of Pieper et al. can be made, for example, according to the following general procedure. First, a slurry containing abrasive grains and binder is introduced to a production tool. Second, a backing is introduced to the outer surface of the production tool such that the slurry wets the front side of the backing. Third, the binder is at least partially cured. Fourth, the production tool is removed from the backing.
U.S. Pat. Nos. 5,174,795 and 5,232,470 (Wiand) teach a planar abrasive article comprising a sheet portion with a plurality of protrusions extending therefrom. Abrasive particles are homogeneously dispersed throughout the moldable material comprising the article. Wiand teaches one embodiment having short protrusions extending 1.6 mm (0.063 in.) from the backing and having a 3.2 mm (0.125 in.) diameter, and another embodiment having short protrusions extending 1.3-1.5 mm (0.05-0.06 in.) from the backing and having a 1.3 mm (0.05 in.) diameter.
G.B. Patent Application No. 2,043,501 (Dawkins) discloses an abrasive article for polishing ophthalmic workpieces. The abrasive article is made by injection molding a mixture of abrasive grains and a thermoplastic binder to form an abrasive article comprising a flexible backing having a plurality of upstanding projections, the ends of which act as operative abrading surfaces.
U.S. Pat. No. 5,427,595 (Pihl et al.) discloses an extruded abrasive filament including a first elongate filament component having a continuous surface throughout its length and including a first hardened organic polymeric material and a second elongate filament component coterminous with the first elongate filament component, including a second hardened organic polymeric material in melt fusion adherent contact with the first elongate filament component along the continuous surface. The second hardened organic polymeric material can be the same or different than the first hardened organic polymeric material. At least one of the first and second hardened organic polymeric materials includes a thermoplastic elastomer having abrasive particles adhered therein. Also disclosed is an abrasive article comprised of at least one abrasive filament mounted to a substrate such as a hub adapted to be rotated at high speed.
Polyamide, also known as “nylon”, filaments were developed in the late 1950's as a synthetic alternative to natural filaments. At about that time an extrusion process was developed for dispersing abrasive particles uniformly in a nylon matrix in the form of a filament (U.S. Pat. Nos. 3,522,342 and 3,947,169). A review of polyamide abrasive filaments is presented by Watts, J. H., “Abrasive Monofilaments-Critical Factors that Affect Brush Tool Performance”, Society of Manufacturing Engineers Technical Paper, 1988, a written version of a presentation by the author at the WESTEC Conference, held Mar. 21-24, 1988. It is known to use conventional inorganic abrasive particles with such polyamide filaments. As explained by Watts, as filaments of this type wear, new abrasive particles are exposed. An abrasive filament brush tool made using a plurality of these filaments is thus regenerated during use. While adequate for many purposes, various polyamides have property limitations which make their use less than optimal for certain applications of abrasive filaments.
U.S. Pat. No. 5,460,883, (Barber, Jr., et al.) describes the use of thermoplastic elastomers in abrasive filaments to reduce or overcome such limitations of polyamide filaments.
An abrasive brush and filaments are described in International Publication No. WO 96/33638 (Johnson et al.), published on Oct. 31, 1996. Johnson et al. report that moldable polymers can be used in brushes, brush segments and filaments. Preferably, the moldable polymer is an organic binder material that is capable of being molded, i.e., it is capable of deforming under heat to form a desired shape. Johnson et al. teach that desirable moldable polymers may be a thermoplastic polymer, a thermosetting polymer, a thermoplastic elastomer, and mixtures thereof. Johnson et al. also teach that thermoplastic elastomers may be used in processes such as injection molding, extrusion, blow molding, and the like. Injection molding, as taught by Johnson et al., provides placing a mixture of pellets including a moldable polymer and, optionally, abrasive particles in a hopper which feeds the mixture into a first or rear side of a screw injector. The softened mixture is then passed into a mold, wherein the screw injector includes a heated barrel for melting the mixture, while a rotating screw within the barrel propels the mixture into the mold. Thus, as described by Johnson et al., injection molding utilizes a single moldable polymer source from which to feed the screw injector and, subsequently, the mold.
SUMMARY OF THE INVENTION
There is a need to provide an abrasive article, such as an abrasive brush, that is easily, rapidly, and inexpensively manufactured. An abrasive article so manufactured preferably provides suitable durability and abrading characteristics. There is also a need to provide an abrasive brush having abrasive particles
3M Innovative Properties Company
Allen Gregory D.
Marcheschi Michael
LandOfFree
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