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  Method and apparatus for refinishing wooden floorsUSPTO Application #: 20080014843Title: Method and apparatus for refinishing wooden floors Abstract: A portable machine is used to abrade the surface of a factory finished wooden floor so the abraded surface may be recoated with a fresh coat of wooden floor finish. Abrasion of the surface provides anchor sites to achieve a strong bond between the pre-existing abraded finish and the fresh coat of wooden floor finish. (end of abstract) Agent: Blackwell Sanders LLP - St. Louis, MO, US Inventors: Michael G. Kramer, Richard B. Strickland, D. Wayne Lee USPTO Applicaton #: 20080014843 - Class: 451350000 (USPTO) Related Patent Categories: Abrading, Frame Or Mount, Portable Abrader, Floor Surfacing Machine The Patent Description & Claims data below is from USPTO Patent Application 20080014843. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED CASES [0001] This application is a continuation-in-part of application Ser. No. 10/907,605 filed on Apr. 7, 2005. BACKGROUND OF THE INVENTION [0002] Factory finished hardwood floors are a growing segment of the wood flooring industry. Factory finished wooden floors, often contain a resilient, wear-resistant topcoat and one or more intermediate coats that are applied to a thin upper veneer of wood. In contrast, conventional on-site finished wooden floors use solid wooden planks. Prior art sanding techniques and abrasive elements used successfully on conventional on-site wooden floors with solid wooden planks have been ineffective when applied to factory finished floors with a thin upper veneer of wood. [0003] Some wood flooring manufacturers have incorporated wear-resistant particles into these factory applied finishes, as a means of giving their product a competitive advantage over solid plank wood floors that are finished on-site. The wear resistant particles in the finish allow factory finished floor manufacturers to provide long wear-through warranties. Traditional floor finishes that are applied on-site to solid plank wood floors typically do not contain wear resistant particles. [0004] Some of the factory finished wooden floors have a nominally flat surface and some have an intentionally uneven surface which is often referred to in the trade as "sculptured". These nominally flat and sculptured floors have their finish applied at the factory as opposed to the traditional method of having a contractor finish the floor on-site after installation. Many factory finished wooden floors also have a slight bevel on the opposing longitudinal edges which is another reason why the surface is referred to as nominally flat. [0005] Traditional wooden floors that are finished on-site are typically solid wooden planks that are about 3/4 inch thick. These on-site finished floors may be sanded with a variety of prior art machines including but not limited to: walk-behind drum sanders, walk-behind belt sanders, walk-behind orbital sanders and/or walk behind rotary sanders. To applicants knowledge, none of the aforementioned prior art sanders use a brush with filaments having an impregnated abrasive to finish solid plank floors that are installed on-site. [0006] The present invention produces an unexpected result when compared with prior art abrasive sleeves, abrasive belts, peel and stick sandpaper and abrasive screens. Wood floors have a grain that is derived from the tree. Some of the grain is hard and some of the grain is soft. The prior art abrasive sleeves, belts, sandpaper and screens are relatively flat to achieve a relatively flat finish on the floor. In other words, they are designed to sand relatively equal amounts of the hard and the soft grain. Some believed that a cylindrical brush, if used on wooden floors would remove more wood from the soft grain and less wood from the hard grain, thus leaving an uneven floor surface, which would be undesirable. Thus for decades, no one is believed to have used cylindrical abrasive brushes on conventional on-site solid wooden plank floors. Some thought that the cylindrical brush of the present invention would have a similar deleterious effect on factory finished wooden floors. In other words, some anticipated that a cylindrical brush would remove more soft grain than hard grain and leave an uneven floor surface, which is undesirable. Unexpectedly, the cylindrical brush of the present invention removes the same amount of finish and/or wood from soft grain and hard grain, on factory finished flooring, leaving a nominally flat surface. Unexpectedly, the cylindrical brush of the present invention, when used on uneven sculptured factory finished floors, does not destroy the sculptured surface. [0007] The aforementioned prior art drum sanders often use replaceable abrasive sleeves that fit over the drum to sand conventional solid plank floors. These prior art abrasive sleeves often rotate from about 1,800 to about 3,000 rpm, which is much too fast for the brushes used in the present invention. These high speeds cause the filaments to fly off the brush of the present invention which limits brush life. [0008] The brush of the present invention rotates from about 750 to about 950 rpm, and optimally about 850 rpm. The aforementioned prior art belt sanders often use circular abrasive belts to sand the floor. The belt sanders, likewise operate as speeds much too fast for the brush of the present invention. The aforementioned prior art orbital sanders often use replaceable peel and stick sandpaper sheets to sand the floor and orbit at about 175 rpm, which is too slow for the brush of the present invention. Orbital sanders also leave undesirable circular scratches in the surface of factory finished floors. The aforementioned prior art rotary sanders often uses replaceable abrasive screens that adhere to a polyester fiber pad to sand the floor. The replaceable screens are coated with an abrasive that functions to sand the floor. Rotary sanders typically operate at about 175 rpm, which as previously mentioned is too slow for the brush of the present invention. [0009] Conventional wooden floors that are finished on-site are uneven and have high and low spots. However, because the planks are thick solid wood, aggressive sanding to eliminate many of the high spots is common using conventional procedures and conventional abrasive elements discussed above. However, factory finished floors have a thin upper veneer that often will not support the aggressive sanding techniques of conventional procedures with conventional abrasive sleeves, abrasive belts, sandpaper and/or abrasive screens. There is a need to develop new procedures and new apparatus that will allow refinishing of factory finished floors with thin upper veneers. [0010] Factory finished hardwood floors come in various thicknesses, but 3/8 inch is common. The thin upper veneer on the factory finished wooden floor may only be 0.125-0.05 inches thick for 3/8 inch flooring. Thicker factory finished hardwood floors of 9/16 inch may only have a upper veneer of 0.160-0.05 inches. The wood under the top veneer is often of a different type or grade to reduce the cost of the factory finished flooring. Conventional walk-behind drum sanders with prior art abrasive sleeves, walk-behind belt sanders with prior art abrasive belts, orbital sanders with prior art peel and stick sandpaper and/or rotary sanders with prior art abrasive screens may sand through the thin veneer of factory finished floors, especially at "high spots" which are discussed below. There is a need for an improved apparatus and method to refinish factory finished wooden flooring to, inter alia, avoid sanding through the thin veneer on high spots. [0011] Various attempts by others have been made to develop ways to recoat and restore the luster to the finish of factory finished wood floors. For example, U.S. Pat. No. 6,663,467 is for a Process and Composition for Abrading Factory finished Floors. This prior art patent discloses an abrading composition that is applied to an area of floor, such as from a spray pump bottle. The wet floor is then either hand abraded with a pad in circular motion or gone over with a rotary buffing machine having a buffing pad. [0012] Another attempt to recoat factory finished floors has been made by BonaKemi USA, Inc. of Aurora, Colo. The BonaKemi web site (www.bonakemi.com) advertises the Prep.TM. recoat adhesion system. The web site describes this product as a specially formulated recoat adhesion system for all types of polyurethane finished hardwood floors, including factory finished floors. According to this web site, the system conditions and prepares the existing finish to optimize adhesion of the new coat of finish. [0013] Another attempt to recoat factory finished floors has been made by Basic Coatings of Des Moines, Iowa. The Basic Coatings website (www.basiccoatings.com) advertises the TyKote Dustless Recoating System as a product suitable for factory finished floors. Material from Basic Coatings describes the process as follows: The surface of the factory finished wooden floor is cleaned with Intensive Floor Treatment, another Basic product, followed by a clear water rinse and cleaning with Squeaky Cleaner, another Basic product. The TyKote bonding agent is then applied to the remaining floor finish and left to dry for an hour or so. Once the TyKote bonding agent is dry the wood floor finish can be applied. However, there is still a need for a better way to solve the problem of worn factory finished wooden floors. [0014] Factory finished floors that come with a nominally flat finish may actually vary up or down by as much as 1/8 of an inch due to irregularities in the sub-floor. Sculptured factory finished floors have intentional irregularities in the surface, for example to give the appearance of a distressed appearance. The process and apparatus of the present invention can be used for several different applications on both nominally flat factory finished wooden floors and sculptured factory finished wooden floors. SUMMARY OF INVENTION [0015] This invention is an apparatus and method that may be use for several applications including: 1) Restoring the luster to nominally flat and sculptured factory finished wooden floors; 2) Restoring the luster to a first site installed finish on nominally flat and sculptured wooden floors that were originally installed with a factory finish; 3) Removing the factory finish from nominally flat and sculptured factory finished wooden floors and refinishing, 4) Removing the first site installed finish from nominally flat and sculptured wooden floors that were originally installed with a factory finish and refinishing and 5) Removing a combined on-site finish and a factory finish from nominally flat and sculptured wooden floors and refinishing. [0016] This invention is a portable machine with a brush having flexible filaments impregnated with a suitable abrasive and various methods for use of this machine on factory finished floors. There are various pitfalls to avoid when dealing with factory finished floors. When the objective is to restore the luster to a factory finish, it is undesirable to remove all of the existing factory finish. The challenge is to avoid abrasion of "high spots" down to bare wood, which will be discussed in greater detail below. In the alternative, when the objective is to remove the factory finish down to bare wood for refinishing, the challenge is to avoid abrasion of "high spots" through the thin upper wooden veneer, as will be discussed in greater detail below. [0017] The present invention uses an easily removable brush with flexible filaments impregnated with suitable abrasives to abrade the surface of the floor. As the brush wears, fresh abrasive is exposed, giving the brush longer life. The brush may also be reversed on the drive shaft to give it longer life. The abrasives are selected from the group including aluminum oxide, silicon carbide and mixtures thereof. To applicant's knowledge, removable brushes with flexible abrasive impregnated filaments are not used to finish wooden floors in prior art on-site installations with solid plank floors. Prior art on-site methods utilize various abrasive elements including: replaceable abrasive drums, replaceable abrasive belts, replaceable sandpaper and/or replaceable abrasive screens which can be quickly dulled by factory finished floors. The prior art abrasive elements were replaced when the abrasive became dull or damaged. The removable brush of the present invention is designed to be easily removed from the machine and changed to another grit to suit the needs of the operator. [0018] A. Restoring the Luster to a Floor Finish. [0019] The process to restore the luster to the floor finish does not require removing all the finish down to bare wood. Instead, some of the existing finish is removed and some of the existing factory finish is left on the floor surface. Microscopic scratches are made in the remaining factory finish to provide anchor sites to achieve a good bond between the pre-existing abraded finish and the new coat and/or coats of wood floor finish. The challenge is to avoid abrading all the way through the factory finish down to bare wood. [0020] The floor unevenness will create "high spots" and "low spots" in the floor surface. Both of these conditions are a challenge when it is time to restore the luster to a factory finished floor. When the filaments of the abrading brush of the present invention encounter "high spots" they bend so the finish on this portion of the floor is not abraded down to bare wood. In the case of "low spots", the abrading brush is designed with filaments long enough to reach into and sufficiently abrade the finish in "low spots" that would be encountered on a typical floor. [0021] Conventional processes which use abrasive sleeves, abrasive belts, peel and stick sandpaper and/or abrasive screens do not perform well on factory finished floors which contain "high spots" and "low spots". When a drum sander with an abrasive sleeve encounters a "high spot" on the floor, it tends to completely remove the finish of a factory finished wooden floor down to the bare wood on the high spot and not necessarily the surrounding floor surface. Similar results may also occur with belt sanders using abrasive belts, orbital sanders using sandpaper and/or rotary sanders using abrasive screens. When restoring the luster to a factory finished floor, it is undesirable to abrade the finish down to bare wood on just the "high spots" because the overall floor coloring is no longer uniform and may need to be restained. It is difficult and often impossible to restain an exposed "high spot" to match the rest of floor. Further, it is time consuming and adds to the expense of the project. When a conventional drum sander with abrasive sleeves, a belt sander with an abrasive belt, an orbital sander with peel and stick sandpaper and/or rotary sander with abrasive screens encounters a "low spot" it may pass right over the area without ever abrading the finish. Once the new top coat of finish is applied, it is unlikely that the finish will adhere properly to the under coat of finish in the area of the "low spot" because little or no abrasion has occurred to allow for a mechanical bond to take place between the two coats of finish. Continue reading... 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