US20070178817A1

US20070178817A1 - Discontinuous abrasive particle releasing surfaces

Info

Publication number: US20070178817A1
Application number: US11/503,058
Authority: US
Inventors: Fred N. Miekka; Bola Ajere; Michael Berner
Original assignee: SMRG
Current assignee: S M R G; SMRG
Priority date: 2006-02-01
Filing date: 2006-08-14
Publication date: 2007-08-02

Abstract

Discontinuous abrasive particle releasing surfaces are disclosed that may be employed in low speed wet grinding, sanding, and polishing operations. The discontinuous abrasive surfaces of the present invention may consist of abrasive containing protrusions attached to rigid or flexible surfaces or alternatively may be comprised of closed cell foam compositions impregnated with abrasive materials such as aluminum oxide. The voids present in the discontinuous abrasive surfaces of the present invention serve to hold water and remove debris. The resulting discontinuous abrasive particle releasing surfaces are long lasting and may be made low in cost.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims benefit of the provisional application filed on Feb. 1, 2006 having application No. 60/764,110 and the provisional application filed on Jul. 5, 2006 having application No. 60/818,571.

BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates to abrasive materials and surfaces. More particularly this invention relates to discontinuous abrasive surfaces employing discrete areas containing abrasive particles that are continuously released in free form during wet low speed sanding, grinding, and polishing operations. The discontinuous abrasive surfaces of the present invention may consist of abrasive containing protrusions attached to rigid or flexible surfaces or alternatively may be comprised of closed cell foam compositions impregnated with abrasive materials such as aluminum oxide. The voids present in the discontinuous abrasive surfaces of the present invention serve to hold water and remove debris.
2. Description of the Related Art
There are numerous methods that may be employed to sand surfaces. One of the more common methods employs sand paper. Sand paper is a thin sheet material usually made of paper that has an abrasive material securely bonded onto one side. Despite its name, the abrasive is rarely if ever sand. Commonly used abrasives such as aluminum oxide and silicon carbide are significantly harder than sand and are therefore more effective. This may be especially true when sanding hard materials such as glass or steel.
Sand paper may be used by hand. This process is often referred to as hand sanding. The process of hand sanding involves using manual labor to repeatedly slide the sand paper back and forth and/or in a circular motion over the surface until smooth. Numerous textures of abrasives are available. Often sanding starts out with a relatively course grade of sand paper of about 80 grit followed by finer grades of several hundred grit to finish the job.
One drawback often associated with sand paper is the production of dust. Sanding surfaces often produces dust that clogs the sand paper and may create an inhalation hazard as well. This is especially true for sanding hazardous materials such as lead paint. One way to alleviate this problem is by using wet or dry Emery cloth. Wet or dry Emery cloth is an abrasive coated cloth having a wide variety of grades. It is designed for use with water thereby reducing clogging effects and significantly or even completely eliminating the production of air bourn dust.
Another drawback with using sand paper is the tendency for the abrasive to become dull and fall off from the sand paper backing surface.
Sanding by hand using sand paper is not always practical owing to the amount of labor required. This is especially true for large jobs that may take a long time resulting in fatigue.
In order to alleviate the worker fatigue issue in hand sanding operations, numerous power sanding techniques and/or equipment have been developed. Drum sanding, belt sanding, disc sanding, and orbital sanding are commonplace. These standard power sanding tools often employ some form of sand paper and therefore often suffer from many of the previously mentioned drawbacks. In particular is the need to change the sanding surface at regular intervals.
Numerous modifications to ordinary sand paper have been made in order to improve the overall process. For example, sand paper having a lowered surface density of abrasive particles is available. This particular sand paper is made by 3M Corporation of ST. Paul Minn. and is designed for use in sanding relatively soft materials that quickly gum up ordinary sand paper. Significant improvements in sand paper life may be realized by reducing the tendency of particulate matter to clog the needed spaces between adjacent abrasive particles.
Another improvement that may be made to ordinary sand paper involves the use of flexible and conformable foam backing. Such backing materials allow the sand paper to conform to surface contours thereby more rapidly smoothing contoured surfaces. Individual pieces of sand paper may be applied to foam pads or conversely, foam pads having previously attached sand paper may be employed. For example, Finishing Buddies (Mona Lisa Products 10770 Moss Ridge Road Houston, Tex., 77043) is a complete sanding tool kit consisting of a steel wool pad, oval sanding disc, and coarse, medium, and fine sanding pads. The oval pad is relatively rigid, and the three other sanding pads have a softer foam backing that has a greater degree of flexibility. This sanding kit is designed for slow hand sanding and finishing operations.
There are numerous flexible sanding surfaces, components, and articles comprised of abrasive materials fixedly attached to flexible foam backings. Of particular interest is a sanding system employing a relatively thin rigid foam backing disclosed in U.S. Pat. No. 6,923,840 and assigned to 3M Innovative Properties Company, St. Paul Minn. (US). U.S. Pat. No. 6,923,840 discloses a flexible abrasive product comprised of an open cell foam backing, a foraminous barrier coating, and a shaped foraminous abrasive coating. The top abrasive coating is discontinuous and allows for holding lubricants such as water as well as spaces for removal of debris.
U.S. Pat. No. 6,949,128 also assigned to 3M, discloses a method for making a foam backed abrasive article having embossed raised areas.
U.S. Pat. No. 3,401,490 discloses a method for forming an abrasive article having a resiliently yielding open cell meltable base which is passed under a heated roll to melt the surface to a desired depth followed by application of abrasive particles to the melted surface. The result is a flexible foam based abrasive article capable of following irregular, uneven, or sunken surfaces.
U.S. Pat. No. 6,997,794 by James Matthew Pontieri discloses a disposable sanding device fabricated as a continuous rope like article adapted for selective segmentation. This device may employ a foam central portion along with an abrasive outer portion. In particular the flexible cylindrical geometry illustrated in several embodiments of the invention lends itself to the hand sanding of difficult to reach contours and may prove especially useful in woodworking applications.
There are numerous flexible foam based cleansing and scouring pads having added abrasive materials. An example of this can be found in U.S. Pat. No. 3,377,151. U.S. Pat. No. 3,377,151 discloses a method for making flexible resilient cleansing and scouring pads having an abrasive surface. A thermoplastic foam web material is hot laminated to abrasive web material. In addition, one or more cleansing materials may be added.
U.S. Pat. No. 3,619,843 discloses sponges having dry impregnated materials. In this invention, impregnated sponges are prepared by a process that deposits particulate material on one surface of the sponge and subsequently pierces the sponge with spikes to form crevices followed by drawing particulate material into the crevices. The result is a modified sponge suitable for surgical and sanitizing applications.
Also of interest are flexible open cell foam scouring and cleaning pads having numerous protrusions. These pads are disclosed in U.S. Pat. No. 4,055,029 by Heinz Kalbow, Lichgasse. The flexible pad has numerous protrusions on the working surface having an abrasive layer. U.S. Pat. No. 4,111,666 also by Heinz Kalbow discloses a method of manufacturing flexible abrasive cleaning pads along with improvements in tear resistance.
U.S. Pat. No. 4,421,526 discloses polyurethane foam cleaning pads composed of a densified flexible sponge like polyurethane foam material impregnated with various cleansing additives. Excessive mixing of the freshly blended polymers inhibits foam formation long enough to add the cleansing ingredients. The resulting pads have added strength due to collapsed, ruptured, and distorted cells along with fibers that result from the specific mixing process employed. The result is an unusually strong dense flexible cleaning pad capable of absorbing substantial amounts of water that releases additives along with absorbed water on gentle squeezing.
U.S. Pat. No. 4,594,362 discloses a dry type textile cleaning article comprised of a friable hydrophilic polyurethane foam with incorporated abrasive particles as well as other additives. The abrasive particles are chemically bonded to the foam using silane coupling agents thereby reducing their tendency to separate from the mass and subsequently damage cloth material.
While the above described examples of foam based abrasive articles provide a wide variety of uses, there exists a need in the art for lightweight semi-rigid or rigid closed cell foam abrasive articles suitable for hand and/or low speed wet sanding, and/or wet grinding, and/or wet polishing operations.
Many of the above described examples outline the use of foam with abrasive materials in order to achieve certain advantageous and desirable properties. Still others outline some of the more simple methods and materials commonly employed in sanding, grinding, and polishing operations. While generally effective for sanding, grinding, and polishing, there exists a need in the industry for further improvements in low speed wet sanding, grinding, and polishing operations. For example, lapping is a process that uses special equipment to grind surfaces to a high degree of flatness. Unfortunately, this equipment tends to be expensive and bulky. In addition, producing a good flat grind may require certain acquired skills to master. This results in difficulties for small shops and individuals in the hobby field in grinding surfaces flat.
Another example where further improvements in low speed wet sanding, grinding, and polishing operations may be realized is in the area of sanding cloths. Flexible abrasive cloth materials such as emery rapidly become dull and shed abrasive particles. Because of this, sanding operations often require several pieces of emery cloth to complete. While making discrete zones of attached adhesive may serve to reduce the tendency of debris to build up in the sanding surface, the issue of rapid dulling and shedding of surface abrasive particles still remains a major issue to be resolved.
Finally, flexible abrasive surfaces employing foam have certain added benefits that may be realized in numerous applications. Many of the earlier patents referenced in this application fall under this class of abrasive surfaces.
Despite numerous advancements in the field of abrasives there is a need for discontinuous abrasive particle releasing surfaces for wet sanding, grinding, and polishing operations.
It is an object of this invention to provide wet low speed sanding, grinding and polishing surfaces.
It is a further object of this invention to provide numerous grades of wet sanding, grinding, and polishing surfaces.
It is a further object of this invention to provide wet sanding, grinding, and polishing surfaces resistant to excess build up of debris
It is a further object of this invention to provide wet sanding, grinding, and polishing surfaces in both rigid and flexible forms.
It is a further object of this invention to provide wet sanding, grinding, and polishing surfaces that are low in cost.
It is a further object of this invention to provide simple methods for producing wet sanding, grinding, and polishing surfaces.
Finally it is an object of this invention to provide wet sanding, grinding, and polishing surfaces that may be used for extended periods of time without wearing out.

SUMMARY OF THE INVENTION

This invention therefore proposes discontinuous abrasive surfaces employing discrete areas containing abrasive particles that are continuously released in free form during wet low speed sanding, grinding, and polishing operations. The discontinuous abrasive surfaces of the present invention may consist of abrasive containing protrusions attached to rigid or flexible surfaces or alternatively may be comprised of closed cell foam compositions impregnated with abrasive materials such as aluminum oxide. The voids present in the discontinuous abrasive surfaces serve to hold water and remove debris.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a lapping surface suitable for grinding surfaces flat.

FIG. 2 shows a blank grinding block having an adhesive zone for mounting disposable lapping surfaces.

FIG. 3 shows a lapping block consisting of a lapping surface adhered to the top of a flat surfaced block.

FIG. 4 shows a cross sectional view of numerous surface protrusions embedded with hard abrasive particles.

FIG. 5 shows a cross sectional view of numerous flat topped surface protrusions embedded with hard abrasive particles.

FIG. 6 shows a sectional view of a low speed sanding disc for a rotary tool.

FIG. 7 shows a hand held abrasive foam sanding block of the present invention.

FIG. 8 shows a hand held abrasive article made entirely out of the foam based abrasive of the present invention.

FIG. 9 shows a sectional view of a low speed wet abrasive foam disc for use with a rotary tool.

FIG. 10 shows an abrasive fabric employing polymeric resin protrusions of the present invention embedded with coarse aluminum oxide.

FIG. 11 shows an abrasive loaded polymeric resin protrusion having a top surface portion containing a pattern of grooves and ridges.

FIG. 12 shows an abrasive fabric glove having numerous abrasive protrusions attached to working surfaces in accordance with the present invention.

FIG. 13 shows a sectional view of a low speed wet sanding disc for a rotary tool having a plurality of layers of surface protrusions comprised of hard abrasive particles dispersed within a softer material matrix.

FIG. 14 shows a sectional view of cloth material for low speed wet sanding having a plurality of layers of surface protrusions comprised of abrasive particles dispersed within a softer material matrix.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a lapping surface suitable for grinding surfaces flat. Lapping surface 2 is comprised of numerous protrusions 4 extending upward from rigid backing laminate 6. Protrusions 4 may take the form of numerous shapes including polygons such as squares and hexagons, spheres, such as those shown in FIG. 4, and/or modified spheres such as those shown in FIG. 5. Furthermore, the top surfaces of protrusions 4 may have added grooves as shown in FIG. 9. It should be noted that protrusions 4 are separated from each other and therefore may be considered to be discontinuous. The spaces formed between individual protrusions 4 provide means for holding water and for the rapid removal of debris. Protrusions 4 may be comprised of a relatively soft matrix material such as a polymer impregnated with abrasive particles possessing a degree of hardness significantly greater than that of the matrix material itself. The result is an abrasive particle releasing surface for low speed wet lapping operations providing good abrasive properties. It should be noted that it may be desirable to control the hardness of the protrusions themselves. Opposite first major surface 2 of rigid backing laminate 6 is a second major surface (not shown) this second major surface may have mounting hardware and/or materials such as pressure sensitive adhesives to facilitate mounting to a more rigid flat substrate surface.
Polymeric resin based materials such as epoxy may be cast in a suitable mold. For example, a laminate construction may be assembled having numerous protruding spherically shaped particles. The laminate may then be treated with a suitable release coating and used to make a silicone rubber mold. Once the mold is cured, the laminate may then be removed. The now vacant mold may then be used to cast a lapping surface. Abrasive powder may be first sprinkled evenly in the numerous voids in the mold that are to become protrusions. Abrasive loaded polymeric resin such as epoxy may then be added on top of the already existing free abrasive particles residing within the individual discrete protrusion cavities within the mold. If desired, further addition of abrasive particles to the epoxy resin in the mold may then be carried out followed by allowing the above described composition to set into a hard mass.
West system 105 epoxy resin (West Systems Inc. PO Box 665 Bay City, Mich. 48707 USA) has been used for producing working prototypes employing aluminum oxide abrasive. It should be noted that aluminum oxide is a dense material and therefore tends toward settling to the bottom of the mold. Since the bottom of the mold represents the tops of the protrusions in the final part, this method of manufacture may be employed to keep numerous abrasive particles on the outer exposed surfaces of the protrusions themselves. This particular configuration may help to facilitate the initial release of abrasive particles. This technique may be employed to improve the initial release of abrasive particles on first time use. Once the process of abrasive particle release starts, it becomes self sustaining.
FIG. 2 shows a blank grinding block having an adhesive zone for mounting disposable lapping surfaces. Block 8 is shown having adhesive pattern 10 on top surface 12. Top surface 12 of block 8 is flat and therefore helps to maintain flatness of the final assembly.
FIG. 3 shows a lapping block 14 consisting of top exposed abrasive particle lapping surface portion 20 (lapping surface 2 of FIG. 1) attached to top flat surface portion 18 of base block portion 16. Exposed abrasive particle releasing lapping surface portion 20 is shown to be larger in area than side surface portion 16 and therefore may be considered a first major surface of lapping block 14. Lapping block 14 has a second major surface (not shown) oppositely facing first major surface 20. Lapping block 14 is shown having side surface portion 16 and top flat surface portion 18. Also shown is disposable lapping pad 20 attached to top surface 18 of block 16.
Lapping block 14 is suitable for lapping small articles flat. The article may be glued to a holder and lapped in a circular motion by hand, or alternatively lapped at a relatively slow rate by machine. Some articles may also be held directly by hand and subsequently lapped flat. In many instances water in pure form or with special additives may be employed in the process. Generally speaking the lapping surfaces of this invention will retain water in the voids between surface protrusions. Employing water as a lubricant may also help to flush debris from the area being used. When finished, the lapping surface may be cleaned of residual debris with running water. When the lapping surface portion 20 of lapping block 14 becomes worn out, it can be replaced at a reasonable cost. Removable attachment means such as pressure sensitive adhesives may be employed to achieve this end.
FIG. 4 shows a cross sectional view of numerous surface protrusions shown in discontinuous arrangement comprised of abrasive particles dispersed within a softer material matrix such as epoxy resin. Laminate backing portion 22 is shown along with attached protrusions 24. Attached protrusions 24 are shown having abrasive particles 25 embedded into softer material matrix portion 27.
FIG. 5 shows a cross sectional view of numerous protrusions having a flat top surface geometry shown in discontinuous arrangement comprised of abrasive particles dispersed within a softer material matrix such as epoxy resin. Laminate backing portion 26 is shown along with attached protrusions 28. Attached protrusions 28 are shown having abrasive particles 29 embedded into softer material matrix portion 31.
FIG. 6 shows a sectional view of a low speed sanding disc for a rotary tool. Abrasive particle releasing disc 33 is shown having abrasive releasing first major top surface portion 37 along with rigid backing portion 35 and central hole 39 for mounting to a shaft (not shown). Top abrasive releasing surface portion 37 is comprised of numerous protrusions 41 fixedly attached to rigid backing portion 35. Protrusions 41 are comprised of hard abrasive particles dispersed within a softer material matrix. Protrusions 41 are shown in greater detail in FIGS. 4 and 5. Bottom surface portion 47 of rigid backing portion 35 may be regarded as a second major surface portion.
Abrasive particle releasing disc 33 is suitable for wet rotary sanding operations. A shaft may be attached using central hole 39 and a threaded screw. The shaft may be subsequently fitted into the chuck of a low speed rotary tool such as a drill. A relatively low speed of about 50 to 500 RPM may be employed to wet sand numerous surfaces. It should be noted that high RPM conditions of 1000 or more may result in excess loss of water employed in wet sanding operations.
FIG. 7 shows a hand held abrasive foam sanding block of the present invention for wet low speed sanding, grinding, and polishing operations. Abrasive foam block 30 is shown having side portion 32 along with exposed abrasive particle releasing surface portion 34. Side portion 32 has a thin skin over the surface as a result of the molding process used to prepare adhesive foam block 30. Exposed abrasive particle releasing surface portion 34 is shown having closed foam cells 36 that have been severed by a sharp knife (not shown) and are therefore exposed. Exposed closed foam cells 36 are made of a rigid material such as polyurethane in order to maintain a rigid geometry during use and form a discontinuous surface for holding water and removing debris during wet sanding, grinding, and polishing operations. The closed cell foam material of exposed abrasive particle releasing surface portion 34 is shown to be larger in area than side surface portion 32 and therefore may be considered a first major surface of abrasive foam block 30. A second major surface (not shown) is on the opposite side from exposed particle releasing surface portion 34 of abrasive foam block 30.
FIG. 8 shows a hand held abrasive article made entirely out of the discontinuous rigid closed cell foam based abrasive material of FIG. 7. Hand held abrasive article 38 is shown having bottom portion 40 along with handle portion 42. Also shown are handle mounts 44 used to attach handle portion 42 to bottom portion 40. It should be noted that hand held abrasive article 38 may be one continuous piece consisting of abrasive foam material that has been formed in a single operation in a suitable mold (not shown). Exposed discontinuous hard abrasive particle releasing surface 49 of hand held abrasive article 38 forms a first major surface and may be used for wet sanding, grinding, and polishing operations. Second major surface 51 is shown opposite of first major surface 49. Second major surface 43 serves as the attachment surface for handle 42 using handle mounts 44.
The abrasive foam compositions of the present invention are intended for low speed wet mechanical as well as wet hand sanding, grinding, and polishing operations. In general, no reinforcement is needed and the compositions may be adjusted to attain desirable levels of rigidity, strength, and rate of wear. Furthermore, the addition of excess abrasive materials to the polymeric foam compositions of the present invention may result in rapid wear degradation of the foam and associated rapid release of abrasive particles. These abrasive particles may then find their way into crevices thereby enhancing sanding, grinding and polishing operations. In order to achieve this end, the abrasive materials may each have a percent composition in the mix that has the above described unique desirable properties. Outlined below are several examples of the abrasive loaded polyurethane closed cell foam compositions of the present invention.

EXAMPLE 1

5.0 grams of foam A polyurethane foam pre-polymer from Plastic Depot (2900 San Fernando Blvd Burbank, Calif. 91054) were placed into a small plastic cup. To this were added 5.0 grams of 70 grit aluminum oxide abrasive. The mixture was then stirred with a wooden popsicle stick until uniform. In a separate plastic cup were placed 5.0 grams of foam B polyurethane pre-polymer from the same source as the foam A. To this were added 5.0 grams of 70 grit aluminum oxide abrasive and the mixture stirred until uniform. Then two mixtures were then combined and stirred until uniform. The resultant mixture was then poured into a small polyethylene container and allowed to foam and subsequently cure. The cured foam composition was then allowed to sit overnight to stabilize. The foam abrasive composition was then removed from the polyethylene container. A small section of the outside portion was cut off with a sharp knife to expose the foam cells underneath the outside skin. A small amount of water was placed on this exposed surface. This wet exposed surface was then used to sand the paint off of a soda can. Removal of the thin paint layer occurred within a few seconds leaving a scratched surface behind. It should be noted that the aluminum surface underneath the paint did not bind up as often happens with sand paper but rather tended to disperse in the water and accumulate in the exposed voids of the foam.

EXAMPLE 2

The experiment of example 1 was repeated with increasing concentrations of 70 grit aluminum oxide abrasive. At a concentration of 70% by weight, the foam composition became exceedingly weak and readily broke off when wet sanding rough surfaces. The resulting particles formed a mixture of broken off foam and free aluminum oxide abrasive. This particular mixture was exceedingly efficient at sanding rough and irregular surfaces.

EXAMPLE 3

The experiment of example 2 was then repeated with 100 grit aluminum oxide abrasive. It was found that a concentration of aluminum oxide of 66% was required to attain similar results.

EXAMPLE 4

The experiment of example 3 was repeated with finely divided aluminum oxide polishing powder. It was found that a concentration of this finely divided aluminum oxide of about 50% by weight was required to disrupt the polyurethane foam to a level sufficient to cause its break up during use. The resulting use of this composition produced good polishing properties to rough wet surfaces.

EXAMPLE 5

5.0 grams of foam A polyurethane foam pre-polymer from Plastic Depot (2900 San Fernando Blvd Burbank, Calif. 91054) were placed into a small plastic cup. To this were added 8.0 grams of finely divided ferric oxide abrasive. The mixture was then stirred with a wooden popsicle stick until uniform. In a separate plastic cup were placed 5.0 grams of foam B polyurethane pre-polymer from the same source as the foam A. To this were added 8.0 grams of finely divided ferric oxide abrasive and the mixture stirred until uniform. The two mixtures were then combined and stirred until uniform. The resultant mixture was then poured into a small polyethylene container and allowed to foam and subsequently cure. The cured foam composition was then allowed to sit overnight to stabilize. The foam abrasive composition was then removed from the polyethylene container. A small section of the outside portion was cut off with a sharp knife to expose the foam cells underneath the outside skin. A small amount of water was placed on this exposed surface. This wet exposed surface was then used to polish rough sanded automotive paint. Polishing was quick with noticeable results occurring within a few seconds leaving a polished surface behind. It should be noted that the resulting debris tended to disperse in the water and accumulate in the exposed voids of the foam.
FIG. 9 shows a sectional view of a low speed wet abrasive foam disc for use with a rotary tool. Abrasive particle releasing foam disc 53 is shown having abrasive releasing first major top surface portion 55 along with rigid backing portion 57 and central hole 59 for mounting to a shaft (not shown). Top abrasive releasing surface portion 55 is comprised of numerous abrasive particles embedded into closed cell foam attached to rigid backing portion 57. Bottom surface portion 61 of rigid backing portion 57 may be regarded as a second major surface portion.
Abrasive particle releasing disc 53 is suitable for wet rotary sanding operations. A shaft may be attached using central hole 59 and a threaded screw. The shaft may be subsequently fitted into the chuck of a low speed rotary tool such as a drill. A relatively low speed of about 50 to 500 RPM may be employed to wet sand numerous surfaces. It should be noted that high RPM conditions of 1000 or more may result in excess loss of water employed in wet sanding operations.
FIG. 10 shows an abrasive fabric 46. Abrasive fabric 46 is comprised of a flexible water absorbent fabric backing layer 48 along with attached abrasive loaded polymeric resin protrusions 50. Abrasive fabric 46 is shown as a discontinuous surface that releases hard abrasive particles during low speed wet sanding, grinding, and polishing operations. The separation of individual abrasive loaded polymeric resin protrusions 50 between each other forms a discontinuous surface. Also shown is material matrix portion 52 in the form of a polymer resin such as epoxy embedded with coarse aluminum oxide abrasive 54 having a hardness significantly greater than polymer matrix portion 52. Abrasive fabric 46 may be used for machine driven sanding surfaces such as belts and discs as well as hand sanding applications.
It should be noted that the protrusions themselves provide points of high pressure that facilitate wet sanding and grinding operations. It should also be noted that water absorbent flexible fabric 48 employed allows individual abrasive loaded polymeric resin protrusions to follow surface contours during wet sanding operations in addition to absorbing and releasing excess water during these same operations. This may be used to significantly control the moisture of surfaces during wet sanding operations. Individual protrusions 54 may have grooves like those shown in FIG. 11.
FIG. 11 shows an abrasive loaded polymeric resin protrusion 56 having a top surface portion 58 containing a pattern of grooves 60. Grooves 60 provide means for holding water and for the subsequent removal of debris in wet low speed sanding, grinding, and polishing operations. Furthermore, ridges 62 resulting from grooves 60 in top surface portion 58 provide for increased pressure at the start of wet sanding operations. This added pressure helps to facilitate the process of dislodging abrasive particles 62 and assures a good start to the wet sanding process. Once ridges 64 wear, abrasive particles 62 will continue to be released during use.
The above described abrasive loaded polymeric resin protrusions of FIG. 9 were prepared in the following manner. A mold pre-form was made in the following manner. A 4″×6″ piece of flat glass was thoroughly cleaned and dried. To this surface were attached Vitreous Glass Mosaic Tiles (Landscape L8⅜″-⅙ LB from Mosaic Mercantile). The tiles were evenly spaced in eleven rows of seven having their widest side facing down against the glass surface. Two part five minute epoxy resin was then used to firmly attach the tiles to the glass surface. It should be noted that the tiles themselves were 0.4″ square at the bottom tapered evenly to 0.325″ square at the top, and had an overall thickness of 0.15″. The top surface had three ridges as shown in FIG. 9. Once hard, the epoxy was allowed to further cure overnight. A thin layer of vegetable oil was applied to the entire tile coated glass surface and the glass placed smooth side down in a 5″×7″ polyethylene flat bottom container. One hundred and fifty grams of two part silicone RTV rubber molding compound (PD-1000-A) from Plastic Depot 2907 San Fernando BLVD Burbank, Calif. 91504 Tel# 818-843-3030) were mixed thoroughly in accordance with the enclosed instructions and carefully poured over the mold pre-form in the polyethylene container. The silicone rubber was allowed to cure at room temperature for twenty four hours. The mold was then removed from the polyethylene container and peeled off from its pre-form. The silicone mold was then thoroughly washed with a strong detergent to remove residual vegetable oil and subsequently allowed to dry.
Fifteen grams of West systems 105 epoxy resin were mixed with 3.0 grams of West systems 205 fast curing catalyst. The mixture was stirred thoroughly followed by the addition of 36 grams of 70 grit coarse aluminum oxide abrasive. The mixture was then stirred until completely uniform. Immediately after mixing the resultant abrasive paste was placed into the voids in the silicone mold. A flat edge was then dragged against the mold surface to level the resin mixture in the voids. The resin was allowed to cure for twenty four hours. Once cured, the abrasive protrusions were removed from the mold and inspected for quality. The best sixty samples were then ground flat on their largest side and attached to the front surface of a cotton glove using West systems 105 epoxy resin and 205 hardener. Unfortunately, the glove tended to absorb the low viscosity resin. The abrasive protrusions were then removed and wiped clean with a paper towel. The glove with the still wet adhesive was then stuffed with paper towels to prevent the resin from gluing the glove shut. The resin was allowed to harden somewhat. The paper towels in the glove were then removed and the resin on the glove allowed to thoroughly cure. Five minute epoxy was then applied to the widest side of each abrasive protrusion and the protrusions glued to the glove at the positions corresponding to the previously cured spots of resin on the glove. This approach worked exceptionally well with the resultant glove having sixty abrasive protrusions firmly attached to the required areas for hand sanding operations.
The above described glove was then tested against numerous surfaces including automotive paint on plastic, automotive paint on metal, aluminum, painted aluminum, and glass. This testing was carried out with and without water. The dry sanding produced numerous coarse scratches in the above mentioned surfaces while the wet sanding was more rapid and complete with more uniform finer sanding. It should be noted that this particular sanding glove rapidly wet sanded all of the above described surfaces by hand in a matter of seconds.
FIG. 12 shows an abrasive fabric glove having numerous discrete abrasive protrusions attached to major working surfaces in accordance with the present invention. Sanding glove 62 is shown having abrasive loaded polymeric resin protrusions 64 that are discontinuous from each other and attached to glove 66 with epoxy resin 68. Also shown are ridges 70 on protrusions 64. Ridges 70 on protrusions 64 provide points of high pressure and help to hold water during the first use. Protrusions 64 consist of polymeric resin portion 72 along with abrasive particle portion 74 thereby forming a mixture of hard abrasive particles dispersed within a softer epoxy resin material matrix.
FIG. 13 shows a sectional view of a low speed wet sanding disc for a rotary tool having a plurality of layers of surface protrusions comprised of hard abrasive particles dispersed within a softer material matrix. Abrasive particle releasing disc 76 is shown having abrasive releasing first major top surface portion 78 along with rigid backing portion 80 and central hole 82 for mounting to a shaft (not shown). Top abrasive releasing surface portion 78 is comprised of numerous protrusions 82 fixedly attached to rigid backing portion 80 forming a first layer 84. A second layer 86 of protrusions 88 are also shown. Protrusions 88 forming second layer 86 are shown fixedly attached to protrusions 82 of first layer 84. Protrusions 82 and 88 are comprised of hard abrasive particles dispersed within a softer material matrix. Protrusions 82 and 88 are shown in greater detail in FIGS. 4 and 5. Bottom surface portion 90 of rigid backing portion 80 may be regarded as a second major surface portion.
FIG. 14 shows a sectional view of fabric material for low speed wet sanding and grinding having a plurality of layers of surface protrusions comprised of abrasive particles dispersed within a softer material matrix. Abrasive particle releasing fabric 92 is shown having abrasive releasing first major top surface portion 94 along with flexible water absorbent fabric portion 96. Top abrasive releasing surface portion 94 is comprised of numerous protrusions 98 fixedly attached to flexible water absorbent fabric portion 96 forming a first layer 100. A second layer 102 of protrusions 104 are also shown. Protrusions 104 forming second layer 102 are shown fixedly attached to protrusions 98 of first layer 100. Protrusions 98 and 104 are comprised of hard abrasive particles dispersed within a softer material matrix. Protrusions 98 and 104 are shown in greater detail in FIGS. 4 and 5. Bottom surface portion 106 of flexible water absorbent fabric portion 96 may be regarded as a second major surface portion.
The above descriptions of FIGS. 13 and 14 outline a plurality of layers. These may be formed by forming a first layer of abrasive containing protrusions followed by adhesion of a second layer on top of the first layer using a suitable adhesive material such as epoxy.
Those skilled in the art will understand that the preceding exemplary embodiments of the present invention provide foundation for numerous alternatives and modifications. These other modifications are also within the scope of the limiting technology of the present invention. Accordingly, the present invention is not limited to that precisely shown and described herein but only to that outlined in the appended claims.
Drawings

Claims

1. A discontinuous abrasive particle releasing surface for low speed wet sanding, grinding, and polishing operations comprising:

a rigid backing having a first major surface and a second major surface;

a plurality of abrasive particle releasing protrusions fixedly attached to said rigid backing to at least one said major surface; whereby said plurality of particle releasing protrusions are comprised of abrasive particles dispersed within a softer material matrix.

2. A discontinuous abrasive particle releasing surface for low speed wet sanding, grinding, and polishing operations as recited in claim 1, wherein said discontinuous abrasive particle releasing surface is removably attached to a second surface.

3. A discontinuous abrasive particle releasing surface for low speed wet sanding, grinding, and polishing operations as recited in claim 1, wherein said discontinuous abrasive particle releasing surface is a lapping surface.

4. A discontinuous abrasive particle releasing surface for low speed wet sanding, grinding, and polishing operations as recited in claim 1, wherein said plurality of protrusions have a flat top surface geometry.

5. A discontinuous abrasive particle releasing surface for low speed wet sanding, grinding, and polishing operations as recited in claim 1, wherein said soft matrix material is a polymer.

6. A discontinuous hard abrasive particle releasing surface for wet low speed sanding, grinding, and polishing operations comprising:

a rigid polymeric closed cell foam substrate having at least one major surface;

said at least one major surface of said rigid polymeric closed cell foam substrate having exposed voids along with a plurality of abrasive particles dispersed within said foam; whereby said plurality of abrasive particles are continuously released in free form during said wet sanding, grinding, and polishing operations.

7. A discontinuous hard abrasive particle releasing surface for wet low speed sanding, grinding, and polishing operations as recited in claim 6 wherein a handle is made entirely of the discontinuous abrasive foam material.

8. A discontinuous hard abrasive particle releasing surface for low speed wet sanding, grinding, and polishing operations comprising:

a flexible backing having a first major surface and a second major surface;

a plurality of protrusions fixedly attached to at least one of said major surfaces; whereby said plurality of protrusions are comprised of abrasive particles dispersed within a softer material matrix.

9. A discontinuous hard abrasive particle releasing surface for low speed wet sanding, grinding, and polishing operations as recited in claim 8, wherein the flexible backing is fabric.

10. A discontinuous hard abrasive particle releasing surface for low speed wet sanding, grinding, and polishing operations as recited in claim 9, wherein the fabric is formed into a glove.

11. A discontinuous hard abrasive particle releasing surface for low speed wet sanding, grinding, and polishing operations as recited in claim 8 wherein the soft material matrix is a polymer.

12. A discontinuous hard abrasive particle releasing surface for low speed wet sanding, grinding, and polishing operations as recited in claim 8 wherein the protrusions have a top surface containing a pattern of groves for holding water and removing debris and ridges for increasing the pressure at the start of wet sanding, grinding and polishing.

13. A discontinuous abrasive particle releasing surface for low speed wet sanding, grinding, and polishing operations as recited in claim 1, wherein said abrasive particle releasing protrusions are formed into a plurality of layers.

14. A discontinuous hard abrasive particle releasing surface for low speed wet sanding, grinding, and polishing operations as recited in claim 8 wherein said plurality of protrusions are formed into a plurality of layers.