Patent Application
20080032603
a is an enlarged cross sectional view of one embodiment of an abrading head of the tool in a disengaged position.
b is an enlarged cross sectional view of the abrading head of the tool in an engaged position.
a is an enlarged cross sectional view of one embodiment of an abrading head of a tool in an “off” position, the abrading head including an on/off switch.
b is an enlarged cross sectional view of the abrading head of
a is a perspective view of an embodiment of a tool of the present disclosure, including a projected light defect locator.
b is an enlarged cross sectional view of the abrading head of
While the above-identified drawing figures set forth several exemplary embodiments of the disclosure, other embodiments are also contemplated. This disclosure presents illustrative embodiments of the present invention by way of representation and not limitation. Numerous other modifications and embodiments can be devised by those skilled in the art which fall within the scope and spirit of the principles of the present disclosure. The drawing figures are not drawn to scale.
Moreover, while embodiments, components, and examples are referred to by the designations “first,” “second,” “third,” etc., it is to be understood that these descriptions are bestowed for convenience of reference and do not imply an order of preference. The designations are presented merely to distinguish between different embodiments for purposes of clarity.
Moreover, directional terms such as down, up, left, right, above, below, etc. are used only for ease of discussion. It is understood that the features discussed may be oriented in any manner.
Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numbers set forth are approximations that can vary depending upon the desired properties using the teachings disclosed herein.
Abrasives are commonly used to grind, sand, polish, and otherwise treat the surfaces of materials such as wood, metal, plastic, and painted and coated surfaces. Abrasive articles include coated abrasives, lapping coated abrasives, non-woven abrasives, and buffing articles, for example. These abrasive articles can be in various forms, such as a disc, a sheet, or a polygonal element. In some embodiments, an abrasive sheet is affixed to or integrally formed with a back-up support pad of resilient material. Moreover, abrasive articles may optionally contain holes or slits to aid in dust and residue extraction.
One embodiment of a device of the present disclosure is an electrically, pneumatically, or hydraulically powered surface treatment or abrading tool. The term “abrading” as used herein includes all methods of material removal due to frictional contact between contacting surfaces in relative motion, such as grinding, sanding, polishing, burnishing, or refining. The relative motion produced by the tool can be a vibratory, straight line, rotary, orbital, or random orbital motion, for example.
A rotary tool simply rotates abrasive disc about a fixed axis. This may cause the abrasive face of the disc to abrade deeper scratches into the surface of the workpiece, because the abrasive face follows the same path during each rotation of the disc. This regular rotary motion can result in deeper, coarser cutting, which may be desirable for some applications, but not for others.
An orbital tool moves the abrasive disc in a revolutionary pattern. Another type of abrasive apparatus of the present disclosure is a random orbital tool. This type of tool combines a rotary and orbital motion which results in a random motion of the abrasive disc with respect to the workpiece. Such a motion is desirable because a random motion of the abrasive disc decreases the likelihood that a regular pattern of deeper scratches will be cut into the surface of the workpiece. As a result, a finer finish may be obtained on the surface of the workpiece.
One method of abrading a workpiece involves moving an abrasive article while urging the abrasive against a workpiece. An abrasive article is generally any cutting device that will level a defect in or on a workpiece. By “abrasive disc” it is meant that the abrasive article is typically circular; however, other shapes (e.g., hexagonal, octagonal or scalloped, for example) can be used without departing from the spirit and scope of the disclosure, and are included within the term “disc.” For example, U.S. Pat. No. 4,920,702 (Kloss et al.) discloses a portable tool having, in one embodiment, a generality triangular back-up pad and abrasive disc that are vibrated.
In the illustrated embodiment, tool 10 is pneumatic and is connected to an air compressor (not shown). In another embodiment, tool 10 is connected to a different power source such as a hydraulic or electrical source. In some embodiments, tool 10 incorporates its own power source (such as a battery) and does not require connection to an external power source.
a is an enlarged cross sectional view of one embodiment of abrading head 14 of the tool 10, in a disengaged position. As shown in more detail, an exemplary embodiment of abrading head 14 includes balancer 56 attached by screw 58. Axis B-B of second shaft 60 moves with ball bearings 62 and 64. Axis B-B is parallel to axis A-A (see
Balancer 56 assists in effecting revolution of second shaft 60 about axis A-A. The speed of rotation of second shaft 60 may depend on parameters such as the amount of force applied to the tool, the material composition and topography of the workpiece, and the abrasive that is used. For example, under very light pressure, second shaft 60 may revolve relatively quickly whereas under a very high load, second shaft 60 may revolve relatively slowly.
In one embodiment, backing plate 66 is attached to the end of abrading head 14 by screws 68. Backing plate 66 typically includes force control device attachment means 70 for attaching force control device 74. A force control device 74 may be affixed to a backing plate 66 in a number of different ways. For example, a pressure sensitive adhesive (PSA) (see U.S. Pat. No. 3,849,949 (Steinhauser et al.), for example); interengaging fastener members, such as a multiplicity of hook portions on the backing plate and a multiplicity of loop portions on the force control device (see U.S. Pat. No. 4,609,581 (Ott), for example); and cooperating male and female fastener members, may be used. Another suitable attachment system is disclosed in commonly assigned U.S. Pat. No. 6,988,941, entitled “Engaging assembly for abrasive back-up pad,” hereby incorporated by reference. In the illustrated embodiment, back-up pad 73 and abrasive disc 72 are in turn attached to force control device 74.
In the illustrated embodiment, skirt 28 is attached to angle housing 32 and backing plate 66 to prevent rotation of abrasive disc 72, thereby resulting in an orbital motion of abrasive disk 72. In another embodiment, skirt 28 may be omitted, and the tool 10 will then exhibit a random orbital motion. The general operating principles of a random orbital tool are further described in commonly assigned U.S. Pat. No. 5,377,455, entitled “Automated random orbital abrading system and method,” and U.S. Pat. No. 4,660,329, entitled “Powered abrading tool,” the contents of both of which are hereby incorporated by reference. It is contemplated that tools using the teachings of the present disclosure may also use other types of motion, such as rotary, straight-line or vibratory motions.
a shows tool 10 in a disengaged position. In this position, springs 76 of stabilizer 29 are relaxed. A bottom surface of movable portion 30 of stabilizer 29 extends below abrasive disc 72.
As illustrated, force control device 74 is mechanically tuned by a spring to cooperate with stabilizer 29. Stabilizer 29 and force control device 74 are constructed so that even if an operator applies more pressure than needed, the construction prevents abrasive disc 72 from contacting workpiece surface 78 with too much force. Thus, stabilizer 29 and force control device 74 work cooperatively to prevent a force of contact between the abrasive disc 72 and the workpiece surface 78 from exceeding a set level. In one embodiment, the force control device 74 has a maximum force control level, and the set level is less than the maximum force control level.
In some embodiments, the springs of the stabilizer exert a greater force than the force control device. In an exemplary embodiment, the springs of the stabilizer may exert about 5 pounds of force, equal to the set level, while the spring of the force control device may exert about 3 pounds of force. This arrangement ensures full contact between the abrasive disc and the workpiece surface (i.e., a substantial portion of the abrasive disc contacts the workpiece), and ensures that the desired pressure (i.e., the “set level”) is transmitted to workpiece surface, even if the springs of the stabilizer are not completely compressed.
In another embodiment, the springs of the stabilizer exert a force that is equal to or greater than the force control device.
In some embodiments, the stabilizer is fixed relative to the tool and does not comprise a spring. When not in use, the force control device is positioned such that the abrasive disc will extend beyond the stabilizer. During use, the fixed stabilizer prevents the springs (or other force control means) of the force control device from being fully compressed such that any additional force applied by the operator cannot transfer to the interface between abrasive disc and the workpiece surface.
In an exemplary embodiment, force control device 74 includes a spring having a certain spring constant. In other embodiments, force control device 74 may be formed from foam, rubber, neoprene, or other material that has a resilient property. While the illustrated embodiment includes a mechanically tuned force control device 74, it is contemplated that the force control device can also be pneumatically tuned using air pressure resistance or hydraulically tuned using an oil valve, for example.
In one embodiment, stabilizer 29 comprises a two-part cylindrical housing surrounding the abrasive disc 72. In an exemplary embodiment, stabilizer 29 prevents tipping of tool 10 and uneven application of abrasive disc 72 to workpiece surface 78. In exemplary embodiments, stabilizer 29 is made of a material such as rubber or plastic that will not itself scratch or otherwise damage workpiece surface 78. While the illustrated mechanism of stabilizer 29 is mechanically tuned to the set level by spring 76, it is also contemplated that stabilizer 29 may be a pneumatically or hydraulically controlled device, for example.
The illustrated embodiment includes back-up pad 73 attached to force control device 74 and an abrasive disc 72 in turn attached to back-up pad 73. The forms of attachment can be the same as or different from those discussed with respect to force control attachment means 70.
Back-up pad 73 may be constructed of a compressible, resilient material, including but not limited to vinyl, cloth, foam such as open or closed cell polymeric foams (such as soft closed cell neoprene foam, open cell polyester foam, polyurethane foam, reticulated or non-reticulated slabstock foams), rubber, or porous thermoplastic polymers, for example, depending on the desired stiffness, conformability, and other properties. Typical polyurethane-based foams include toluene diisocyanate (TDI) based foam and methylene di (or bis) phenyl diisocyanate (MDI) based foam. A softer and/or thicker back-up pad 73 can result in a finer finish and better conform to surface curves or irregularities in workpiece surface 78. In another embodiment, back-up pad 73 may be eliminated and abrasive disc 72 may be attached directly to force control device 74.
Suitable exemplary abrasive articles for abrasive disc 72 are disclosed in commonly assigned U.S. Pat. No. 6,231,629, entitled “Abrasive article for providing a clear surface finish on glass;” U.S. Pat. No. 6,312,484, entitled “Nonwoven abrasive articles and method of preparing same;” and U.S. Pat. No. 5,454,844, entitled “Abrasive article, a process of making same, and a method of using same to finish a workpiece surface,” all hereby incorporated by reference. Other suitable abrasive discs are commercially available from 3M Company, St. Paul, Minn., under the trade designations “Trizact” and “Finesse-it.”
For some applications, it is desirable that a small abrasive disc 72 be used so that the sanded spot requires less subsequent buffing. In an exemplary embodiment, abrasive disc 72 is a round or scalloped edge disc with a diameter between 0.5 inch (12.7 mm) and 1.0 inch (25.4 mm).
The illustrated embodiment includes a suction or vacuum device that operates through vacuum hose 82 to remove the abrasion residue and/or lubricant during or after abrasion. If such residue or lubricant is not removed, it can contaminate a buffing pad that is subsequently used, thereby potentially resulting in unwanted scratches during the buffing process.
a is an enlarged cross sectional view of one embodiment of an abrading head of a tool in an “off” position, the abrading head including an on/off switch 84.
In one embodiment, abrasive disc 72 moves as long as switch 84 is activated. In another embodiment, switch 84 is connected to a timer, computer, or other processor that automatically operates moves abrasive disc 72 for a specified period of time, for example about three seconds. If more operator control is desired, an indicator light or audible buzzer can instead be used to alert the operator that a specified amount of time has elapsed.
In an exemplary embodiment, movable portion 30 of stabilizer 29 also serves as a defect locator. By surrounding the defect on workpiece surface 78 with movable portion 30, an operator can be assured that the defect will be treated. In an exemplary embodiment, movable portion 30 is formed from a transparent material that allows an operator to see through movable portion 30 to confirm that the workpiece defect is within the area to be abraded.
In a case with purely rotary motion, the area of abrasive disc 72 may be about the same as the area within movable portion 30. In a case with orbital, random orbital, or other motion, the area of abrasive disc 72 may be smaller than the area within movable portion 30. In other embodiments, a defect locator may be provided in the form of a light or laser image that projects onto the workpiece surface 78, for example.
a is a perspective view of an embodiment of a tool 10 of the present disclosure, including a projected light defect locator 86.
All patents, patent applications, provisional applications, and publications referred to or cited herein are incorporated by reference in their entirety, including all figures and tables, to the extent they are not inconsistent with the explicit teachings of this specification.
It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application. For example, while tool 10 is illustrated as an angled tool, it is also contemplated that tool 10 may be a palm held tool. Additionally, while tool 10 is described in some embodiments as a handheld tool, it is also contemplated that tool 10 may be robotically or otherwise automatically operated.
