Patent Application
20070141969
The present invention relates generally to hand-held, manually-operated, sanding tools that use a sheet of abrasive material such as sandpaper.
Manually-operated hand sanding tools, such as sanding blocks, are commonly used with abrasive sheets, such as conventional sandpaper, to hand sand or finish a work surface. A commercially available sanding block is the 3M™ Rubber Sanding Block available from 3M Company, St. Paul, Minn. Hand sanding tools may include a foam interface pad that is adhesively bonded to the working face of the sanding tool. Such interface pads, however, suffer from one or more drawbacks or shortcomings. It would be desirable to provide a hand-held, manually-operated, sanding tool that includes an interface pad that overcomes the drawbacks and shortcomings of sanding tools having adhesively bonded foam interface pads.
The present invention provides a hand-held, manually-operated, sanding tool for use with a replaceable sheet-like abrasive material that includes a base member formed of a first material, a molded interface pad formed of a second injection moldable material provided on the base member, thereby defining a working face against which the sheet-like abrasive material is arranged, and a retaining mechanism arranged to maintain the sheet-like abrasive material in operative relation with the interface pad.
In one aspect, the first material has a Shore hardness that is greater than the Shore hardness of the second material (i.e. the interface pad is softer than the base member). In a more specific aspect, the first material has a Shore D hardness of greater than about 30, and the second material has a Shore A hardness of less than about 95.
In one embodiment, the interface pad is a polymeric material. In a more specific embodiment, the interface pad is an elastomeric material. In another aspect, the interface pad includes a textured working surface opposite the base member. In more specific aspects, the interface pad working face includes a macroscopically three-dimensional surface topography. The surface topography may comprise a random three-dimensional surface topography or it may comprise a regular non-random pattern defined by raised regions and recessed regions.
In another aspect, the base member contains slots and the interface pad includes extensions extending into the slots, thereby to form a secure connection between the base member and the interface pad.
In yet another aspect, the present invention provides a method of making a hand-held, manually-operated, sanding tool for use with a replaceable sheet-like abrasive material comprising a base member formed of a first material, a molded interface pad formed of a second injection moldable material provided on the base member, thereby defining a working face against which the sheet-like abrasive material is arranged, and a retaining mechanism arranged to maintain the sheet-like abrasive material in operative relation with the interface pad, wherein the method comprises the steps of providing a sanding tool including a base member having a working face, and forming an interface pad on the base member by injection molding an elastomeric material over the working face.
Advantages of certain embodiments of the invention include improved sanding capability, improved product design flexibility (that is, the product design can be more easily tailored or adapted to a specific end-use application), easier and less expensive manufacturing, and a sanding tool that is easier and more comfortable to use.
The present invention will be further described with reference to the accompanying drawings, in which:
a and 4b are plan views showing alternate three-dimensional surface topographies for the interface pad.
Referring now to the drawings, wherein like reference numerals refer to like or corresponding parts throughout the several views,
The sanding tool 2 shown and described herein is described more fully in U.S. patent application Ser. No. 11/117,932 filed Apr. 29, 2005, the entire contents of which are hereby incorporated by reference. For the present invention, however, the sanding tool 2 generally is not particularly significant as long as it is capable of including an interface pad and includes certain basic features such as the ability to receive and retain a sheet-like abrasive material. Thus, it will be understood that the sanding tool 2 shown and described below is intended to represent any sanding tool capable of having a molded interface pad.
The sanding tool 2 includes a base member 4 and a pair of clamping mechanisms 6, 8 connected with opposed ends of the base member 4. Although the sanding tool 2 is shown with clamping mechanisms 6, 8 at both ends, it will be recognized that one or both of the clamping mechanisms 6, 8 may be replaced with a conventional mechanism for securing the abrasive sheet-like material 40 to the tool. It will also be recognized that although the base member 4 is shown as being rectangular, it may also be square or other shapes that lend themselves for use with conventional abrasive sheets.
The base member 4 has first 10 and second 12 opposed ends and a generally planar bottom surface 14. Each end 10, 12 of the base member 4 has an inclined or angled contact surface 16, 18, respectively, opposite the bottom surface 14. In this manner, the contact surfaces 16, 18 and bottom surface 14 form an acute angle relative to the associated adjacent end 10, 12, respectively.
Each clamping mechanism 6, 8 is pivotally connected with opposite ends 10, 12 of the base member 4 adjacent the contact surface 16, 18, respectively, thereby defining a jaw into which the ends 40a, 40b of a sheet-like abrasive material 40 may be inserted. Each clamping mechanism 6, 8 is movable between a closed position shown in
Each clamping mechanism 6, 8 includes a flexible tensioning member 22, 24 arranged to face the associated contact surface 16, 18. Arranged in this manner, as the clamping mechanisms 6, 8 are lowered toward the base member 4 to secure the abrasive material 40 to the tool 2, the terminal edges of the tensioning members 22, 24 slidably engage the contact surfaces 16, 18. Thus, when an end 40a, 40b of the abrasive sheet 40 is inserted in the gap 20, 21 between the base member 4 and a clamping mechanism 6, 8, and the clamping mechanism is moved from its open position to the closed position, the edge of the tensioning members 22, 24 will frictionally engage the end 40a, 40b of the sheet of abrasive material 40.
As the clamping mechanisms 6, 8 are further urged toward the contact surfaces 16, 18, the tensioning members 22, 24 grip the respective ends of the abrasive sheet 40a, 40b and move it upwardly along the inclined contact surfaces 16, 18 away from the associated end 10, 12, thereby drawing the sheet of abrasive material further into the gap 20, 21. In addition, as the clamping mechanisms 6, 8 are urged against the contact surfaces 16, 18, the tensioning members 22, 24 bow or flex such that the bowed surface of the tensioning members 22, 24 will engage the contact surfaces 16, 18, thereby increasing the overall contact surface area between the tensioning members 22, 24 and the sheet of abrasive material 40. In this manner, slack in the abrasive sheet 40 is taken up, thereby tightening the fit of the abrasive sheet 40 against the bottom 14 of the base member 4.
In the illustrated embodiment, the tensioning members 22, 24 are thin flexible strips of metal, such as a leaf spring, that generally return to their original positions when the applied force is released. Other materials such as a stiff resilient rubber or synthetic plastic material may also be used. To distribute the force applied by the tensioning members 22, 24 to the ends abrasive sheet 40a, 40b evenly (both during the installation of the abrasive sheet 40 onto the tool and while the abrasive sheet is being held onto the tool), the tensioning members 22, 24 extend continuously across the entire width of the clamping mechanisms 6, 8. By distributing the force in this manner, the tensioning members 22, 24 have a reduced tendency to tear or otherwise damage the abrasive sheet material 40.
To further reduce the likelihood that the ends of the tensioning members 22, 24 will dig into the abrasive sheet 40, and thereby possibly damage the abrasive sheet, in an alternative embodiment, the tensioning members 22, 24 may be curved or bowed inwardly such that the tensioning members 22, 24 have curved surfaces that face the contact surfaces 16, 18, and engage the contact surfaces when the clamping mechanisms 22, 24 are closed.
In accordance with a characterizing aspect of the sanding tool 2, a molded interface pad 26 is provided on the bottom surface of the base member 4. The interface pad 26 defines the surface against which the sheet-like abrasive material 40 is secured. By providing a molded interface pad 26, the base member 4 and interface pad 26 form an integrally molded body including an upper portion defined by the base member 4, and a lower portion defined by the interface pad 26. The base member 4 is typically formed of a first polymeric material, and the interface pad 26 is typically formed of a second polymeric material. The second polymeric material used to form the interface pad 26 is typically softer than the material used to form the base member 4. The molded interface pad 26 may be formed of any moldable material but is typically a soft, resiliently-flexible, elastomeric, injection moldable material. Suitable injection moldable materials include natural and synthetic rubbers including latex and butyl rubber, thermoplastic elastomers such as polyurethane elastomers, thermoplastic vulcanizate, and thermoplastic rubber. Suitable materials for the interface pad 26 typically have a Shore A hardness of less than about 95 and, more typically, less than about 70. A suitable material for the molded interface pad 26 is available from Advanced Elastomer Systems, an affiliate of ExxonMobil Chemical, under the trade designation Santoprene.
Generally, the base member 4 is formed of a material having a Shore hardness that is greater than the Shore hardness of the material used to form the interface pad. Suitable materials for the base member include hard synthetic plastic materials, typically thermo set or thermoplastic materials such as ABS (acrylonitrile butadiene styrene), polypropylene, polyethylene, and blends containing such materials. Suitable materials for the base member 4 typically have a Shore D hardness of greater than about 30. A suitable material for the base member 4 is available from GE Plastics under the trade designation Cycolac and Cycoloy (an ABS polycarbonate blend).
Alternatively, base member 4 and the interface pad 26 may be formed via a chemical bond. When attached by a chemical bond, the interface between the base member 4 and the interface pad 26 may be generally planar (i.e. the base member 4 and the interface pad 26 each include generally planar surfaces that are attached to each other) or the interface may include structural features such as those described above to further enhance the interconnection between the base member and the interface pad 26. The chemical bond is formed by selecting compatible materials that form a strong chemical bond.
As shown in
The combination of the base member 4 and the interface pad 26 may be formed, for example, using known multi-material injection molding techniques including co-injection molding, overmolding, and multi-shot molding. For example, the base member 4 may be formed by injection molding a suitable material, such as ABS, into a mold to form the base member 4, and the interface pad 26 may be formed by injection molding a suitable material, such as Santoprene, to form the interface pad 26. Alternatively, the base member 4 may be formed by casting or other known techniques.
Injection molding the interface pad 26 offers a number of advantages over the use of conventional interface pads, which are foam pads that are adhesively bonded to the sanding tool 2. First, because the molded interface pad is injection molded, the additional steps of die cutting a foam sheet to the appropriate size and adhesively bonding the foam pad to the bottom of the base member 4 are eliminated. This simplifies the assembly process and also eliminates the raw material costs associated with the foam pad and adhesive. Injection molding the interface pad 26 also reduces the likelihood of failures between the interface pad and the base member 4 (i.e. injection molding provides a chemical and/or mechanical bond between the interface pad 26 and base member 4 that is unlikely to allow the interface pad 26 to inadvertently separate from the base member 4). The injection molded interface pad 26 may also include a variety of textures and/or patterns, it may be formed of any number of suitable moldable polymer materials depending on the desired durability and conformability properties, and it may be formed in a variety of colors or thicknesses, thereby greatly increasing the design options and design flexibility of the tool, and further allowing the tool design to be easily tailored for specific end uses.
The sanding tool 2 also includes a handle 46. In the illustrated embodiment, the handle 46 includes a neck portion 46a that extends upwardly from a central region of the base member 4, and includes an enlarged head portion 46b located at the end of the neck 46a that defines a knob 48 that can be readily grasped by a user to maneuver and control the movement of the tool 2. To provide the user with a more comfortable grip, the knob 48 portion of the handle 46 preferably comprises an interior region 48a formed of a relatively hard first material and a peripheral region 48b formed of a relatively soft rubber-like second material that is easier to grip and thereby provides the user with improved handling. The first relatively hard material, may be, for example, a hard synthetic plastic, and the relatively soft second material may be, for example, a thermoplastic elastomer, rubber, rubber-like materials or foam.
The tool 2, including the base member 4, clamping mechanisms 6, 8 and handle 46, may be formed of any suitable material including, for example, wood, metal, synthetic plastic, or a stiff rubber.
Those of ordinary skill in the art may appreciate that various changes and modifications may be made to the invention described above without deviating from the inventive concept. For example, it will be recognized that the size of the tool may be adapted so it can be used with the various standard sizes of commercially available abrasive sheets. Thus, the scope of the present invention should not be limited to the structures described in this application, but only by the structures described by the language of the claims and the equivalents of those structures.
