Abrading – Frame or mount – Portable abrader
Reexamination Certificate
2000-08-09
2002-12-31
Wilson, Lee (Department: 3723)
Abrading
Frame or mount
Portable abrader
C451S359000, C451S456000, C451S538000
Reexamination Certificate
active
06500057
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to abrasive devices. Stated more particularly, the present patent discloses and protects a removably attachable abrasive disk, which may be used in combination with a particularly designed sanding pad, that is particularly designed for use relative to motorized rotary drywall sanding tools.
BACKGROUND OF THE INVENTION
One knowledgeable in the art of drywall installation will be well aware that, after the joints between adjacent panels have been filled and taped, the proper installation of drywall requires that the installer sand each joint to reduce it to the level of each adjacent drywall panel thereby smoothing it over such that all evidence of the joint is eliminated after painting.
In the past, and still to a lesser extent today, this necessary sanding has been performed manually, typically with a sheet of sandpaper wrapped around a sanding block. To improve reach, sanding blocks have been hingedly coupled to an end of an elongate pole. As any person who has engaged in either method of sanding will attest, manual sanding by either method quickly proves to be laborious and tiresome.
Advantageously, a number of prior art inventors have developed motorized sanders that retain a typically round or rectangular article of abrasive material, such as sandpaper, and rotate or reciprocate the abrasive sanding article rapidly. With this, the abrasive sanding article can be applied to a drywall panel to be sanded thereby improving a worker's speed and efficiency. Indeed, a number of motorized sanders have been disclosed that are directed particularly to the art of drywall sanding. By way of example, a motorized drywall sander and improvements thereto are described in U.S. Pat. Nos. 4,782,632 and 5,239,783, both to Matechuk and both entitled “Drywall Sander.”
Typically, the abrasive sanding article employed relative to motorized drywall sanders comprises an annular abrasive sanding disk with a concentric annular cutout in the center thereof. When the abrasive sanding article comprises a disk, a back-up pad is normally used to mount or attach the abrasive sanding disk to the drywall sander. Certain prior art back-up pads have a first side to which the abrasive sanding disc is attached and a second side from which a bolt or screw extends to couple to the sanding head of the drywall sander. In other cases, the sanding head has an abrasive sanding disc adhered to a sanding pad, and the two are mounted concentrically on a sanding drive plate such that the abrasive sanding disk can be driven rotatably by a flexible drive shaft. The sanding pad and abrasive sanding disk can be mounted in contact with a sanding drive plate in a shroud by a washer and nut that threadedly engage a retaining spindle that extends from the sanding head. Alternatively, the sanding pad and abrasive sanding disk can be fixed in place by a retaining bolt and washer that pass through the central aperture in the pad and disk and into engagement with the sanding drive plate.
Unfortunately, a number of problems derive from these prior art constructions. Indeed, since the initial introduction of motorized drywall sanders, practitioners in the art have been confronted with issues relating to the attachment, wear, and removal and replacement of the abrasive sanding panels that are coupled to the sanding head of motorized drywall sanders. For example, removing and replacing the sanding pad and abrasive sanding disk on prior art drywall sanders typically requires a user to employ a tool, such as a screwdriver or wrench. This inevitably results in inconvenience and work stoppage for the user.
Furthermore, the central apertures in the sanding pad and the abrasive sanding disk commonly increase the vulnerability of the abrasive sanding disk, and possibly the sanding pad, to tearing when the drywall sander encounters a significant irregularity, such as an electrical outlet or the like, in the surface to be sanded. Not only is a tear in the abrasive sanding disk detrimental because it compels early replacement of the disk, but it is also problematic because the material used to cover drywall tape and to fill the joints between adjacent panels and in screw indentations is easily abraded. Also, the paper surface of the drywall panels can be damaged easily when sanding. A torn or otherwise damaged abrasive sanding disk can quickly result in scoring or other damage to the surface. Absent time consuming repair, such damage mars the appearance of the finished work.
A number of solutions to the problem of providing a readily removable and replaceable abrasive sanding disk have been attempted. For example, U.S. Pat. No. 5,239,783 discloses attaching the abrasive sanding disk to a drive plate by a twist-lock, bayonet-type fastener that takes the place of the retaining bolt of earlier devices. However useful, such a fastener nonetheless leaves uncured the problems that derive from having a central aperture in the abrasive sanding disk and the expense resulting from having to replace the abrasive sanding disk and sanding pad unitarily.
Other prior art inventors have developed systems for removably coupling the abrasive sanding disk to the sanding pad by means of hook and loop fasteners. Under these systems, hook fasteners are disposed on a facing surface of either the abrasive sanding disk or the sanding pad while loop fasteners are disposed on a facing surface of the other of the abrasive sanding disk and sanding pad. With this, the abrasive sanding disk can be removed and replaced relative to the sanding pad by pulling the hook fasteners out of engagement with the loop fasteners. Unfortunately, such devices exhibit a number of problems. For example, the hooks and loops in such devices commonly become clogged with sanding debris and the like.
Yet another flawed practice that has been used in the past is to bond the sanding disk to the sanding pad by use of what is termed a feathering adhesive. Such a practice is described particularly in U.S. Pat. No. 4,558,542 to Marton for a “Stick-On Abrasive Disc.” Unfortunately, this practice is disadvantageous for a number of reasons. For example, a user must apply the adhesive or glue both to the disk and to the backup pad by applying it to each individually or by applying the glue to the abrasive sanding disk and then rubbing the disk against the sanding pad to spread the adhesive evenly.
By doing so, adhesive can get onto the abrasive side of the disk whereupon it can get onto and mar or damage the surface to be sanded. The adhesive also can plug up the sanding disk. Still further, the sandpaper in many cases tears up in use and also when the operator tries to remove it from the backup pad thereby leaving small pieces or chunks of the abrasive sanding disk. Consequently, completely removing the sanding disk from the sanding pad is nearly impossible whereby a user must glue a new disk over the remaining portions of previous disks. With this, the new disk does not lie flatly and presents an uneven and unbalanced operative surface that can lead to a marking of the surface to be sanded, uneven wear on the abrasive sanding disk, and a tearing of the disk during use.
A still further deficiency exhibited by prior art abrasive sanding disks for drywall derives from their overall configuration. As was noted above, drywall abrasive sanding disks are manufactured as round disks with a concentric, round aperture formed therein. That round aperture is necessary to allow access to the fastener arrangement that fixes the sanding pad in place. Disadvantageously, the central aperture presents an additional edge on the abrasive sanding disk that can, and often does, catch on anomalies, such as an open utility box in a sheet of drywall, in a surface to be sanded. With this, the disks often tear apart thereby leading to added expense and loss of active work time.
In light of the foregoing, one will appreciate that, notwithstanding the plurality of abrasive structures that have been disclosed by the prior art, there remains a need for an abrasive sandin
O'Connell Law Firm
Wilson Lee
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