Abrading – Flexible-member tool – per se – Interrupted or composite work face
Reexamination Certificate
2000-04-13
2002-03-05
Banks, Derris H. (Department: 3723)
Abrading
Flexible-member tool, per se
Interrupted or composite work face
C451S550000, C451S533000
Reexamination Certificate
active
06352471
ABSTRACT:
TECHNICAL FIELD
The present invention relates to abrasive filaments, methods of making the abrasive filaments and methods of refining a surface with the abrasive filaments. The abrasive filaments comprise a thermoplastic matrix and plastic abrasive particles.
BACKGROUND OF THE INVENTION
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. 5,427,595, Pihl et al., addresses such limitations and describes the use of thermoplastic elastomers in abrasive filaments to reduce or overcome such limitations. The filaments of Pihl et al. include a core component and a sheath component which are coextruded. Either or both of the core and sheath includes abrasive particles adhered therein. Pihl et al. teaches the use of conventional inorganic abrasive particles, although the claims of Pihl et al. are not limited to any particular type of abrasive particle.
U.S. Pat. No. 5,460,883, Barber, Jr., et al., also addresses the limitations of polyamides and describes the use of thermoplastic elastomers in abrasive filaments to reduce or overcome such limitations. The filaments of Barber et al. include a preformed core component and a sheath component coated onto the core to form a composite filament. The coated sheath includes abrasive particles adhered therein. Barber et al. teaches the use of conventional inorganic abrasive particles, although the claims of Barber et al. are not limited to any particular type of abrasive particle.
Brushes incorporating abrasive bristles or filaments 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 or filaments that contact the substrate. Abrasive particles can be added to bristles to increase their abrasiveness. The brushes may be made as follows. A mixture of abrasive particles and any suitable thermoplastic binder may be combined and then extruded to form a bristle or abrasive filament. The abrasive filament is then cut to the desired length. A plurality of these abrasive filaments 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.
The abrasive particles typically employed in abrasive filaments and brushes described above have been limited to inorganic particles which necessarily have a high hardness, e.g. greater than 7 and usually greater than 9 on the Mohs hardness scale. The abrasive particles are sufficiently temperature resistant so as not to be deleteriously affected by the bristle or filament manufacturing process. Such abrasive particles are used in abrasive filaments and brushes to refine the surface of a workpiece. In some instances, this refinement is to remove a portion of the workpiece. In other instances, this refinement is to remove unwanted material (e.g., debris, oil residue, oxide layer, paint, etc.) from the workpiece surface. In some applications, it is desired to remove this unwanted material without any removal or abrasion of the underlying workpiece. However the abrasive particles in the abrasive filaments can be so “aggressive” that the abrasive filaments remove the unwanted material along with the workpiece surface.
U.S. Pat. Nos. 3,090,061 and 3,134,122 to Charvat disclose the use of plastic beads on hard wire bristles to maintain the desired spacing of the bristles when assembled into a brush. Charvat teaches that this is effective to properly space and control the bristles to prevent undue compacting of the brush face and to assure equal frequency of tip contacts per unit length of brush face. The preferred brush bristle taught by Charvat is a steel wire have a Knoop hardness of at least 600, and in some cases in excess of 700 and even in excess of 800. Charvat also teaches that the bristle material may comprise any suitable brush bristle, including nylon and glass filament bristles, and that the beads need not be apertured bodies on the bristles, but may be spaced globules and protuberances adhered to the bristles which are not necessarily concentric therewith. The plastic beads and bristles are coated with a thin plastic coating. Charvat does not teach or suggest that the plastic bead spacer or buffer can instead be used as an abrasive particle. In fact, Charvat teaches the use of bristle materials that are much harder and more abrasive than the plastic beads, and also suggests including conventional inorganic abrasive particles in the plastic beads. Charvat teaches that the plastic coating and beads will erode during operation and that the protruding bristle ends are adapted to operate on the work in the manner of a true brush.
What is desired is a filament having abrasive particles that can remove a foreign material from a workpiece surface efficiently without any damage to the underlying workpiece, or provide a desired fine finish to the workpiece surface, and in which the abrasive particles are sufficiently durable to withstand the filament manufacturing process.
SUMMARY OF THE INVENTION
This invention pertains to novel abrasive filaments including plastic abrasive particles, brush constructions containing such abrasive filaments, methods of making such abrasive filaments, and methods of refining a workpiece surface using the brush construction.
One embodiment pertains to an abrasive filament, comprising plastic abrasive particles interspersed in a thermoplastic matrix. In one preferred embodiment of the abrasive filament, the plastic abrasive particles have a greater hardness than the thermoplastic matrix
Regarding this first embodiment, there are four major types of abrasive filaments. In the first type, the plastic abrasive particles are interspersed nearly uniformly and preferably uniformly throughout the thermoplastic matrix. In this first type, this results in a substantially homogeneous abrasive filament. In the second, third and fourth types, the abrasive filament comprises a sheath and a core. In the second type, the sheath comprises the thermoplastic matrix having the plastic abrasive particles interspersed throughout at least a portion thereof The core can comprise either a second thermoplastic material coextruded with the sheath, or a preformed core having the sheath coated over it. In the third type, the core comprises the thermoplastic matrix having the plastic abrasive particles interspersed throughout at least a portion thereof and the sheath comprises a second thermoplastic material. In the fourth type, the sheath and core both comprise a thermoplastic matrix having plastic abrasive particles interspersed throughout at least a portion thereof In these four embodiments, either the thermoplastic matrix and/or the plastic abrasive particles may be different between the sheath and core.
The term “interspersed” means that the abrasive particles are embedded within and located throughout the thermoplastic material that forms the filament. In the case of the core/sheath embodiments, “interspersed” means that the abrasive particles are embedded within and located throughout the thermoplastic matrix that
Bange Donna W.
Johnson David E.
Liepa Mara E.
Pihl Richard M.
3M Innovative Properties Company
Allen Gregory D.
Banks Derris H.
LandOfFree
Abrasive brush with filaments having plastic abrasive... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Abrasive brush with filaments having plastic abrasive..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Abrasive brush with filaments having plastic abrasive... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2855313