Patent Publication Number: US-6988940-B1

Title: Dustless sander

Description:
FIELD OF THE INVENTION 
   The present invention relates to sanding, abrading and polishing apparatus in general. More particularly the invention relates to sanding apparatus which also vacuum cleans the debris produced by sanding and even more particularly but not exclusively to sanding apparatus used in drywall installation and repair. 
   BACKGROUND OF THE INVENTION 
   Sanding generates dust and the more vigorous the removal of material from a target of abrasion, the greater the amounts of dust generated. This dust is first airborne and can remain in the air for some time before settling. While airborne the dust is a hazard to people and requires filtering masks and other protective gear to be worn by workers and anyone else in the environment. Dust settling out of the air onto whatever surface it may drift or be blown requires laborious and time consuming effort to clean up and remove for disposal. Even if a room is sealed and surfaces protected with drop cloths or the like, the dust which falls on the workers, and the dust raised in the folding or rolling up of the drop cloths, etc., is, to some degree at the very least, lifted into the air again to settle again. This in turn requires repeated sweeping, scrubbing, and dusting of all furniture and of all surfaces both horizontal and vertical (walls, ceilings, floors) to finally clean an area. 
   Various attempts have been made to minimize the dust entering the general area and thus minimizing the amount of dust which will settle out of the air. These attempts have consisted of attempting to pull abraded debris and finer particulate dust by means of a vacuum stream after the dust has been generated by the abrading. In some designs of prior art grooves are cut into a rigid tool holding an abrasive screen. The grooves are cut in an attempt to channel debris to an exit after the dust&#39;s production. Some dust always escapes from the borders of the tool and the rigidity of the tool creates other problems: Suction between the rigid plate and the surface to be abraded can cause the tool to hesitate and to stick to that surface and the rigidity of the tool can contribute to gouging the surface to be abraded. Additional appliances have been offered to collect the dust which escapes from the borders of these devices, such as skirts or shrouds surrounding the tool. These devices add to the weight of the device and still fail to collect all the debris. In another offering the sides of the tool are raised to provide vacuum holes on the sides as well as the face of the device. The abrading material is held above the tool by a porous support but the channeling remains inefficient by relying again on the channeling grooves to exhaust the particulate dust and again, the weight of the device is increased. 
   All of the above devices are directed to sanding only planar surfaces. This restricts the use of the tool to such situations where the target surface is not only flat but of sufficient area to accommodate the dimensions of the tool. All of the above devices can be urged against a target surface at only one level of pressure, thus precluding a choice between a light sanding and hard planing away of unwanted material. 
   Devices of this sort all require replaceable abrasive screens. Wear and tear and general fatigue of these screens is exacerbated when the screen is pressed against the wall by the rigid face of the device holding the screen. When back and forth movement is part of the sanding process the fatigue is increased. Another factor contributing to the fatigue is the mechanism by which the screens are attached to the device. Generally, the screen is affixed to the tool by clamping the end edges of the screen between the jaws of a spring loaded metal clamp or forcing the ends of the screen into a groove cut in hard rubber, or by holding the ends of the screen in position around the face of the tool and securing it there by clamps on either side of the tool which are tightened by turning wing nuts to close the clamps. The edges of all these clamping mechanisms create blades which can tear the abrasive screen. All of these methods of fastening are also difficult and cumbersome and therefore time consuming. 
   These and other examples of similar prior art are described in U.S. Pat. No. 5,283,988 of Brown, U.S. Pat. No. 5,440,616 of Harrington et al., U.S. Pat. No. 4,071,981 of Champayne, U.S. Pat. No. 4,697,389 of Romine, U.S. Pat. No. 5,245,797 of Milkie, U.S. Pat. No. 5,540,616 of Thayer, U.S. Pat. No. 4,765,099 of Tanner, U.S. Pat. No. 4,937,984 of Taranto, U.S. Pat. No. 4,680,895 of Roestenberg, and U.S. Pat. No. 4,799,385 of Hulsing et al. 
   However, the aforementioned devices do not describe a dustless sander wherein the head of the sander, an abrasive screen supported by a malleable, air permeable cushion, projects outwardly from the body of the sander supported by a flat funnel-like platform rotating on the end of a hollow shaft, including a plurality of containers which are stacked one within the other and wherein the two containers embrace and swivel with the platform around the hollow shaft, wherein further a vacuumed stream of air draws debris not only from the working surface but also from the peripherally surrounding area before the debris escapes into the atmosphere. 
   OBJECTS OF THE INVENTION 
   It is an object of the present invention to provide a manual, vacuum-enabled, dustless sander and polisher designed primarily, but not exclusively, for working on plaster, joint compound or similar substances used in drywall installation and repair. 
   It is another object of the present invention to provide a sander capable of virtually total cleaning capability of abraded debris, which capability is realized at any angle of vertical or horizontal use, and above or below the person using the device i.e., on floors, walls or ceilings. 
   A further object of the device is to minimize the weight of the device, making general use, and especially overhead use, less tiring to the worker. 
   Another object is to provide a device which glides more easily over working surfaces than previous devices where a gripping effect, caused by suction between the sander face and the working surface, causes those devices to stall or stick to the working surface. 
   Yet another object is to reduce the fatigue on the abrasive screen by avoiding the grinding of the abrasive screen between a hard sander face and the working surface. 
   Another object is to provide a sander effective not only on flat surfaces but also on curved surfaces, surfaces in or on corners, and on rounded surfaces. 
   Yet another object is greater ease of attaching and detaching the disposable abrasive screen common to these sanding devices and known to those familiar with the art. 
   Another and related object is reduction of fatigue to abrasive screen caused by clamping arrangements of prior art. 
   A still further object is to provide a sander which allows for varying degrees of pressure of the sanding screen against the working surface with no loss of abrading effectiveness or vacuum cleaning power. 
   SUMMARY OF THE INVENTION 
   These objects and others apparent to those skilled in the art are achieved by projecting the head of the sander, an abrasive screen supported by a malleable, air permeable cushion, above the body of the sander. The cushion is supported by a flat funnel-like platform which includes a bored hub, wherein the bored hub of the flat funnel-like platform rotates in a position of use around a flanged pipe inserted into the open end of a hollow shaft. The screen is held in place above the cushion and over the platform by inserting the end edges of the screen into the space between the walls of two containers which loosely embrace the platform. The containers are stacked one within the other and rest easily and loosely within each other. The containers swivel with the platform around the hollow shaft. These containers constitute the body of the sander by which the sander, in one embodiment, may be held. The inner of the containers is threaded at its point of rotation on the hollow shaft. The outer of the containers is fixed at one axis on the hollow shaft. Thus, turning the hollow shaft drives the inner container downward into the outer container, thereby trapping and locking the inserted end edges of the screen in place between the walls of the containers. A vacuumed stream of air draws debris not only from the working surface but also from the peripherally surrounding area before the debris escapes into the atmosphere. The debris is captured and drawn by vacuumed air and pulled through the abrasive screen, the supporting cushion, the funnel platform, the hollow shaft and then through the vacuum line attached to the hollow shaft and finally through the vacuum line to a shop vacuum cleaner or conventional vacuum cleaner capable of fine particulate collection. 
   In a preferred embodiment, the sander includes a shaft having a distal end and an opposite proximal end. A lower container is disposed within the housing, with the lower container having a plurality of walls and a base, and the lower container base having a hole therein. An upper container is disposed within the lower container, with the upper container having a plurality of walls and a base, and the upper container base having a hole therein, so that the upper container hole is substantially aligned with the lower container hole. A rotatable platform is located within the upper container and an air-permeable malleable cushion contacts the platform and is located within the second container. To accomplish abrasion, an air-permeable abrasive screen is temporarily secured between the upper container and the lower container. 
   A portion of the shaft is substantially perpendicular to the lower container base. 
   The walls of the lower container are preferably tapered at an angle greater than ninety degrees with respect to the lower container base; and the walls of the upper container are tapered such that the walls of the upper container are substantially parallel with the walls of the lower container. Additionally, the shaft is substantially aligned with the upper container hole and the lower container hole. 
   The platform further includes a hole substantially aligned with the shaft, the upper container hole, and the lower container hole wherein a flanged pipe resides in the platform hole. The shaft has a threaded portion and the upper container has a hub having threads corresponding with the threaded portion of the shaft. A flanged support on the shaft separates the threaded portion of the shaft from a remainder of the shaft, so that the flanged pipe and the flanged support delineate a range of lateral movement of the upper container. A lower container flange is secured to the shaft, so that the lower container flange limits lateral movement of the lower container. Preferably an adhesive such as glue secures the lower container flange to the shaft. A fastener, such as a set-screw, secures the lower container flange to the shaft. 
   A first portion of the lower container flange and a second portion of the lower container flange are interlocked to secure the lower container flange to the shaft. Furthermore, a base of the platform is tapered towards the platform hole. Also, a portion of the air-permeable abrasive resilient screen is secured between the walls of the upper container and the of walls of the lower container. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention can best be understood in connection with the accompanying drawings. It is noted that the invention is not limited to the precise embodiments shown in drawings, in which: 
       FIG. 1  is an overall perspective view of a preferred embodiment of the invention in use with arrows illustrating the vacuum stream drawing debris into the sander; 
       FIG. 2  is an overall perspective view with the sanding screen detached from the sander and the sander detached from the vacuum line; 
       FIG. 3  is an exploded view of the sander; 
       FIG. 4  is a partially cut away side view of sander with abrasive screen detached at arrow; 
       FIG. 5  is another partially cut away side view of sander with abrasive screen attached and locked in place; 
       FIG. 6  is a cut away side view of detail marked 6 in  FIG. 5 ; 
       FIG. 7  is a side view of device at minimal compression against target surface; 
       FIG. 8  is a side view of device at greatest compression against target surface; 
       FIG. 9  is a top view of the sander in use with arrows indicating path of debris into the sander; and, 
       FIG. 10  is an exploded view of a sander kit. 
   

   DETAILED DESCRIPTION OF THE DRAWINGS 
   This invention is a manual, vacuum-enabled dustless sander, designated generally by reference numeral  10 , which by means of vacuumed air draws all the debris created by sanding into the head of the sander and then through the central column  28  of the sander  10  and then via the vacuum hose  36  into the collection canister of a shop or standard vacuum cleaner. 
     FIG. 1  illustrates a preferred embodiment of the dustless sander  10  in use on a working surface with arrows indicating the inward flow of air carrying debris into the sander  10 . 
     FIG. 2 . illustrates the dustless sander with the abrasive screen  12  detached and shows the path for attachment of the abrasive screen  12  into the body of the sander  10 .  FIG. 2 . also shows the sander  10  detached from the vacuum line  36 . 
   Referring to  FIG. 3 , wherein an exploded view of the sander  10  illustrates the disposition of sander components on and around the central column  28 . In this embodiment the material of all the parts is plastic. In a heavy-duty embodiment, steel or other metals, or combinations of materials may be preferred. In varying embodiments still other different materials may be preferred, even paper composites, such as cardboard, may be indicated for some lighter duty applications. 
   The construction of the sander is organized on the central column  28 , a hollow round shaft which provides support for the components on its outer surface and a channel for vacuumed air through its inner surface. The central column  28  is threaded at one end. The threaded end will be considered the upper end of the column  28  and the upper end of the sander  10 . Two containers  20  and  30  rotate on the column  28 . Both containers have bases of similar size and both have walls which taper outward in the upward direction so that one may rest within the other. The upper container  20  rotates on the column  28  and travels a certain length of the central column  28  by means of thread  24  cut into the external surface of the central column  28  and thread cut into the internal surface of a bored hub  22  in the base of the upper container  20 . The thread  24  on the column is of a distance only great enough to move the upper container  20  from its open position downward into the lower container  30  to its closed position where the walls of the upper container  20  are pulled firmly against the walls of the lower container  30 . A flange  26  at the bottom of the threaded portion  24  of the central column  28  prevents the upper container  20  from pressing any more than as above described into the lower container  30 . The flange also serves as a barrier to prevent the lower container  30  from traveling along the threaded portion  24  of the column  28 . The lower container  30  rotates freely on the column  28  held to a fixed path of rotation on the column  28  between the flange  26  at the bottom of the threaded portion  24  of the column  28  and the flange  34  attached to the column  28  at a position on the column  28  beneath the lower container  30 . The flange  34  may be attached to the column  28  by means of a set screw or snap-on fitting or glue. 
   A platform  18  with four walls and a hole in its base performs as a funnel and is made to rotate on the top of the column  28 , by means of a flanged pipe  16 , the narrow length of which passes through the hole in the platform  18  and into opening  27  of the top end of the column  28 . The flanged pipe  16  is snugly held at a fixed position inside the column  28  by friction. The platform  18  rotates freely around the length of the flanged pipe  16  between the top of the column  28  and the flange of the flanged pipe  16 . 
   As illustrated in  FIG. 4 , a cutaway view of the head of the sander, the rotating platform  18  supports a resilient, air permeable cushion  14 . A replaceable abrasive screen  12  is held in place above the cushion. 
   The cushion  14  is composed of loosely woven non-adhering plastic yarn-like filaments and constructed in a manner which creates resiliency and unimpeded passage of air through the cushion  14 . The cushion  14  is similar to plastic scrubbing pads used for cleaning cooking pots and pans. The cushion  14  is of sufficient size so that the top of the cushion  14  rises above the top of the upper container  20 . Resiliency of the cushion permits varying degrees of pressure to be exerted against the abrasive screen  12  and thus to abrading. As pressure urges the sanding head against a working surface, the cushion  14  and the abrasive screen  12  conform, by degree of pressure applied, to the shape of the platform but at its most dense compression the structure of the cushion  14  still allows unhindered passage of air through itself. 
     FIG. 7  and  FIG. 8  illustrate the behavior of the sander head under varying degrees of pressure. Further, the malleability of the sander head, the cushion and the abrasive screen, allows the sander head to shape itself to the working surface: planar, curved or cornered, while maintaining air flow through itself and thereby maintains complete cleaning capability of differing working surfaces. 
   The cushion  14  may be affixed to the platform  18  by adhesive. The attachment is executed in a manner which does not impede passage of air through the cushion  14  to the hole in the center of the platform  18 . 
   The various components of the sander  10  are assembled by turning the upper end of the central column  28  into the thread of the upper container  20 , then sliding the lower container  30  over the upper container  20  so that the lower container  30  rests loosely outside the upper container  20 . The flange  34  may then be affixed to the central column  28  below the lower container  30  so that both containers  20  and  30 , resting within each other, easily rotate on the central column  28 . The rotating platform  18  is attached to the top of the central column  28  by means of the flanged pipe  16 . The platform rests just within the borders of the upper container so that the platform  18  rotates with and within the two containers. The two containers constitute the body and handle of the sander. Placing the abrasive screen  12  above the cushion  14  and then inserting the end edges of the screen  14  into the gap between the walls of the upper container  20  and lower container  30 , and then turning the central column  28 , thereby driving the upper container  20 , by means of threading  24 , down and into the lower container  30 , locks the screen  14  in place. 
   The locking of the abrasive screen  12  is illustrated more particularly in  FIG. 4  where the arrow indicates the point of insertion of the screen into the gap between the walls of the two containers  20  and  30  and in  FIG. 5  where the circle marked 6 shows the screen  12  locked between the walls of the two containers  20  and  30 . 
     FIG. 6  is a detail of  FIG. 5  showing the screen trapped in place. 
   To operate the sander, the vacuum line  36  is attached to the lower end of the central column  28 . A stream of air drawn through the vacuum line pulls debris abraded by the sander  10  through the sander  10  and through the vacuum line  36  to a vacuum cleaner. 
     FIG. 9  shows an optional ergonomically shaped handle  28   a  for the vacuum line  36 . Handle  28   a  may be curved in shape, and may have an easily gripped elastomeric or other textural outer covering. 
     FIG. 10  shows a kit for retail display or consumer storage of the components of the present invention. For example, central column  28 , having containers  20  and  30  attached thereto, can be stored within the display box, along with fresh sand paper sheets  12 . 
   As will be apparent to those familiar with the art this invention has been described in terms of one embodiment. Variations may be incorporated or added onto the basic idea without departing from the spirit and/or ambit of the invention.