Abstract:
An Adaptive Dust Shield Device having Zero Standoff Capability for rotary grinders having a bearing housing and an axial groove around the bearing housing. The dust shield has a cover molded from a single shot. The cover has a plurality of upstanding flexible fingers, in multiples of four, which extend upward from the cover. A door is formed in one side of the dust shield cover to allow the user to use the dust shield in zero clearance situations. The flexible fingers have a defined width and are separated apart from each other by a space between each one. The width of the space is less than the defined width of the flexible fingers. A stretchable fitting ring fits onto the bearing housing of the grinder and under the flexible fingers. The flexible fingers are secured onto the stretchable fitting ring by a securing fastener. There are a plurality of vent holes formed in the top wall that are selectively pluggable with plug elements.

Description:
[0001]    This application is filed within one year of, and claims priority to Provisional Application Ser. No. 62/092,119, filed Dec. 15, 2014. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates generally to power hand tools and, more specifically, to an Adaptive Dust Shield Device having Zero Standoff Capability. 
         [0004]    2. Description of Related Art 
         [0005]    Rotary grinders and similar rotary power tools are used extensively in industry. More specifically, angle type grinders/sanders having grinding discs or pads, are used for grinding concrete, fiberglass, wood, steel, removing asbestos, and body filler in automobile shops. Such grinders/sanders are also used for making boats and similar products. In use, these grinders create large quantities of dust that are both a fire hazard and a health hazard. Wood dust, for example, can be very explosive over a wide range of concentrations and is a known fire hazard. Hot metal grindings are particularly dangerous as fire starters. Both wood dust and metal filings, as well as asbestos particles, fiberglass and body filler particles, create known health hazards to users of the grinders and to others in the immediate environment. It is known that concrete dust, as typically generated in great quantities from grinding concrete, is a principal cause of pulmonary silicosis. 
         [0006]    Grinder discs and pads often rotate in excess of 7,000 revolutions per minute (RPM). Grinding pads that use a sponge type backing material create a hazard where parts or particles from the backing material break off and are shot from the rotating disc tangently at a high rate of speed. It is often necessary to use a rotary grinder to grind into corners or against surfaces that have side edges that can cause particles of the foam backing material to break off from the high speed rotating disc and hit the operator or other persons or equipment in the immediate area. 
         [0007]    A dust shield described in U.S. Pat. No. 5,125,190 approached this problem and solved it to some extent. It has an upstanding attachment collar [reference character 16 of U.S. Pat. No. 5,125,190] which had a diameter chosen to fit onto the bearing housing [reference character 38 of U.S. Pat. No. 5,125,190] of a variety of different grinders. Grinders from varying manufacturers have different diameters for their respective bearing housing. Typical diameters of bearing housings range from one and one-half inch to three inches, and therefore a one-size attachment collar on the dust shield would not accommodate the varying bearing housings. Consequently, several different models of the dust shield, each having different collar diameters, had to be manufactured for the various make grinders or requires an adapted. This, of course, increases manufacturing costs and adds to inventory of a supplier and end-user since most end-users have more than one grinder and more than one make. 
         [0008]    Without the adapter, the retailer generally must carry up to 40 SKUs (stock keeping units) to cover all the grinders made. With the adapter, the retailer will need only 6 stocking units, one for each of the major disc diameters of 2, 3, 5, 6, 7 and 8 inches. Space in a retail store is very valuable, and therefore the reduction of SKUs adds value to the adapter because it can reduce the amount of space needed to provide a line of dust shields that can fit all grinders. 
         [0009]    Additionally, the grinding surface of different brands of grinders with different grinding disks varies in distance from the bearing housing of the grinder where the dust shield is attached. The dust shield of U.S. Pat. No. 5,125,190 was not readily capable of a distance adjustment to bring the grinding surface down to where it can be of effective use or, in some cases, any use at all. The collar (reference character 16 of U.S. Pat. No. 5,125,190) had to be individually and carefully sanded down such that its lower edge (reference character 35 of U.S. Pat. No. 5,125,190) was accordingly raised thereby bringing the grinding surface out to point of use. Cutting the skirt, improper sanding, or improper measurements would in essence ruin the dust shield and be a waste of time and money. 
         [0010]    Additionally, the plastics formulation used in the manufacture of the adaptive dust shield is such that, if cutting the adaptive dust shield is necessary, it can easily be cut with ordinary household scissors without ruining the adaptive dust shield in its entirety. The formulation provides for greater flexibility, thereby eliminating much of the need to make distance adjustments of the fitting ring into and away from the bearing housing and into and away on the upstanding fingers. 
         [0011]      FIG. 1  is an exploded perspective view of the adaptive dust shield device of U.S. Pat. No. 8,282,447  100  and a conventional angle grinder  60 . The dust shield  100  attaches to the bearing housing  68  of the grinder  60 . In order to accommodate the widest variety of grinder  60  models, the dust shield  100  may be used with a split fitting ring  110 , that slips over the bearing housing  68  before the ring formed from the upstanding fingers  178  are slipped thereover. The securing fastener  88  is then attached to encircle the upstanding fingers  178 , fitting ring  110 , and bearing housing  68 , and tightened around the combination. This securely holds the dust shield device  100  to the grinder. An external hose  82  from the user&#39;s vacuum system attaches to the exit opening  86  of the exhaust port  80 . The air vents  75  and angled slots  184  allow air to flow in to the internal chamber under the cover  170  in order to create sufficient airflow through the system and into the external vacuum system through the exhaust port  80 . It also prevents the creation of too much suction on the bottom of the cover  170 , which tends to make the cover want to stick to the surface that the user is working above. 
         [0012]    Through experience with the dust shield  100 , it has been noticed that in certain circumstances, it is necessary to cut, grind or polish in “zero clearance” or “zero standoff” conditions. An example of a zero clearance condition would be where the user needs to grind a floor up to where it meets a wall or other vertical obstruction. In such a case, the outer periphery of the grinding wheel needs to be exposed, because otherwise the dust shield  100  would prevent the user from reaching all the way to the wall/vertical obstruction. Historically, the user would simply remove the dust shield  100  from the grinder while doing any zero clearance sections. As should be apparent, removal of the dust shield for any reason during operation is dangerous and unhealthy. 
         [0013]    What is needed, then, is an adaptive dust shield for angle grinders that can accommodate grinding in zero clearance situations without the need to remove the dust shield from the grinder. 
       SUMMARY OF THE INVENTION 
       [0014]    In light of the aforementioned problems associated with the prior devices and systems, it is an object of the present invention to provide an Adaptive Dust Shield Device having Zero Standoff Capability. The adaptive dust shield is generally for rotary grinders having a bearing housing and an axial groove around the bearing housing. The dust shield should be formed in a “single shot” molding process from durable material such as vinyl or the like, with a wall thickness substantially thicker than were the dust shield covers of the prior devices. The adaptive dust shield has a cover with a defined diameter and may have an upstanding collar with a Width-X on top of the cover where Width-X is substantially less than said defined diameter. A plurality of upstanding flexible fingers with a Height-H and in multiples of four extend upward from the top of and around the upstanding collar. These plurality of upstanding flexible fingers have a Width-W 2  and are separated apart from each other defining a space between each one of these plurality of upstanding flexible fingers wherein this space has a Width-W 1  and wherein Width-W 1  is less than Width-W 2 . A stretchable, rubber-like fitting ring is adapted to be stretched if necessary and to fit onto the bearing housing of the grinder. The outside diameter of the fitting ring is adapted to fit into the plurality of upstanding flexible fingers. Being flexible, the plurality of upstanding flexible fingers may flex inward, toward the fitting ring, or outward, away and around the outside diameter of the fitting ring, and be secured onto the fitting ring by a suitable securing fastener. Tightening the securing fastener over the upstanding flexible fingers compresses them into the fitting ring and the fitting ring into the groove of the bearing housing of the grinder. There should be a door element formed in at least one side of the dust shield cover. The door element should be able to be opened when the user wishes to expose a portion of the outer periphery of the rotating tool (blade or grinding wheel, etc.) so that the user can keep the dust shield on the grinder when grinding in zero clearance situations. The door element should be made as an integral part of the dust shield cover when manufactured, with a “living hinge” formed from hinge elements molded to interconnect the door element with the base of the dust shield cover. The dust shield should also be provided with a peg that can be used to retain the door element in the opened position, so that the user does not need to use his/her hands to keep the door element open. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The objects and features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages, may best be understood by reference to the following description, taken in connection with the accompanying drawings, of which: 
           [0016]      FIG. 1  is an exploded perspective view of the adaptive dust shield device of U.S. Pat. No. 8,282,447 and a conventional angle grinder; 
           [0017]      FIG. 2  is an exploded perspective view of a preferred embodiment of the adaptive dust shield having zero standoff capability of the present invention and a conventional angle grinder; 
           [0018]      FIG. 3  is a top view of the cover of the shield of  FIG. 2 ; 
           [0019]      FIG. 4  is a bottom view of the cover of  FIG. 3 ; 
           [0020]      FIG. 5  is a top view of the cover of  FIGS. 2 and 3  depicting the door element in the opened position; and 
           [0021]      FIG. 6  is a perspective view of the cover of  FIGS. 3-5  having the door element in the opened position. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0022]    The following description is provided to enable any person skilled in the art to make and use the invention and sets forth the best modes contemplated by the inventor of carrying out his invention. Various modifications, however, will remain readily apparent to those skilled in the art, since the generic principles of the present invention have been defined herein specifically to provide an Adaptive Dust Shield Device having Zero Standoff Capability. 
         [0023]    The present invention can best be understood by initial consideration of  FIG. 2 . 1    FIG. 2  is an exploded perspective view of a preferred embodiment of the adaptive dust shield having zero standoff capability of the present invention  100 A and a conventional angle grinder  60 . As with the shield [ 100 ], a fitting ring  110  and securing fastener  88  are a part of the kit for the purpose described in more detail below.  1 As used throughout this disclosure, element numbers enclosed in square brackets [ ] indicates that the referenced element is not shown in the instant drawing figure, but rather is displayed elsewhere in another drawing figure. 
         [0024]    While shield [ 100 ] was formed with numerous air vents [ 75 ], as well as angled slots [ 184 ] in order to provide supply air to the vacuum source, in the instant design  100 A, there are likely to be fewer air vents  75  and no angled slots [ 184 ] formed in the upper portion  72  of cover  170 A. This reduction in potential airflow through the device  100 A is enabled because the cover  170 A has a door formed in it that can be opened and closed, as will be depicted and described below. When that door is in the open position, quite a bit of air will flow in through the opening [ 43 ] and past the grinder wheel. If there were as many air vents  75  as in the prior device [ 100 ], there would be the risk that insufficient vacuum (and therefore dust capturing) would be present within the cover  170 A. Also, the hose adapter  82  may include a relief vent that will allow air into the vacuum hose (downstream of the dust shield  100 A). 
         [0025]    In this simplified design (i.e. for simplification of the molding process), there is preferably a single sloped portion  72  interconnecting the upper portion  72  with the skirt  79 . 
         [0026]    Experience has shown that multiples of 4 such upstanding fingers  178 A provide for better results because they can adapt easily to both round bearing housings  68  and square bearing housings alike [not illustrated] 
         [0027]    Width-A of applicant&#39;s adaptive dust shield  100 A is generally set to be close to the largest diameter of the bearing housings of the largest grinders. As such, Width-A [upstanding flexible fingers  178 A] of applicant&#39;s adaptive dust shield  100 A should generally range from approximately 2.00-inches to about 3.00-inches. It can thereby (with application of the stretchable fitting ring  110 , if necessary) accommodate virtually all diameter sizes of bearing housing and not cause a pinch-off of the fingers or sliding off of the dust shield. Use of the stretchable fitting ring  110 , where necessary, builds up small diameter bearing housings to allow the upstanding flexible fingers to compress and secure, with application of the securing member, the dust shield to virtually any grinder. 
         [0028]    The inside diameter [Width-C] of the fitting ring  110  should be roughly the same as the smallest commercially available bearing housing  68  (i.e., from approximately 1.50 inches to approximately 2.00 inches). The fitting ring  110  should be made of a stretchable material [like a rubber band] or a flexible material such that it will fit over bearing housing  68  diameters which are greater than the inside diameter of the fitting ring  110 . 
         [0029]    The most suitable materials for the fitting ring  110 , for the functions above described of stretching and flexing and compressing, include, but are not limited to, any flexible vinyl or rubber compositions of such flexibility to permit an expansion or stretching of the fitting ring  110 , a cutting of the fitting ring  110 , and a compression of the fitting ring when the clamp  88  is tightened around the upstanding fingers  178 A to permit the upstanding fingers to compress into and “grip” the fitting ring  110  and for the fitting ring  110  to compress around the bearing housing  68  and, very importantly, into the groove  69  in the bearing housing  68  of most conventional grinders  60 . 
         [0030]    This gripping, compression by the upstanding fingers  178 A into the fitting ring  110  and of the fitting ring  110  into the groove  69  creates a clearly defined “mechanical connection” among all the components and prevents any rotational or vertical movement of the cover  170 A around the fitting ring  110  or around the bearing housing  68 . The groove  69  of typical grinders  60  generally is an annular groove perpendicular to the axis of rotation or may be a slot-type groove which is parallel to the axis of rotation. In either case, the mechanical connection as described above is created. 
         [0031]    In situations where the inside diameter of the fitting ring  110  is greater than the diameter of the bearing housing  68 , the fitting ring  110  easily slips thereover. The upstanding fingers  178 A of the cover  170 A are spread if necessary and placed around the outside diameter of the fitting ring  110  and then released thereon. A suitable securing fastener  88 , such as a hose clamp, is placed around the outside diameter of the upstanding fingers  178 . It should be understood that the securing fastener  88  may be placed loosely around the upstanding fingers  178 A before placement of the upstanding fingers  178 A around the outside diameter of the fitting ring  110  to facilitate the process. 
         [0032]    In situations where the inside diameter of the fitting ring  110  is considerably smaller than the outside diameter of the bearing housing  68 , because of the composition of the fitting ring  110 , a user may cut through the fitting ring  110  to thereby permit that person to spread out the two ends of the fitting ring  110  and by so doing to increase the size of its inside diameter. The user then places the fitting ring  110  over and onto the bearing housing  68  and releases the spread ends causing them to retract onto the bearing housing. The steps of placement of cover  170 A and securing fastener  88 , as described above, follow. 
         [0033]    Additionally, in situations where the outside diameter of the bearing housing  68  is considerably smaller than the inside diameter of the fitting ring  110 , the user may merely cut off one or more segments of the fitting ring  110  until a suitably sized inside diameter for the fitting ring  110  is established. In cases where the outside diameter of the bearing housing  68  is extremely small, a second fitting ring  110  may be placed and secured over the first fitting ring. The clamping, compressing, and squeezing as described above caused by tightening of the securing fastener  88  establish a secure mechanical connection between all these parts. 
         [0034]    The exhaust port  80 A in this design is somewhat different from the port [ 80 ] of the prior device. It is oriented so that its axis is parallel to the axis of the skirt  79  and upstanding fingers  178 A so that the cover  170 A can be molded in a single step. The tangentially-oriented port [ 80 ] makes such a single shot molding process virtually impossible. The ability to manufacture the cover  170 A in a single shot molding process substantially reduces the manufacturing cost of the cover  170 A. Re-designing the port  80 A allows the cover  170 A to be formed with a simple A-B mold (one that opens and closes and shoots out a part). If molded with the side mounted exhaust port [ 80 ], a slide would be required. When the mold is closed, the slide (which is actuated by hydraulics or a solenoid) is forced into place. This allows the plastic to form the exhaust port. The slide is then withdrawn and then the two parts of the tool (mold) are separated and the part is ejected. This adds great cost to the manufacture of the tool and also presents a hazard when molding. If for any reason the slide doesn&#39;t withdraw at the proper time and the mold opens with it in place, the mold will almost certainly be badly damaged. 
         [0035]    Because the exit opening  86  is oriented straight up (i.e. parallel to the axis of the arbor  64 ), an optional hose adapter  82  may be provided to interconnect the exhaust port  80 A with the vacuum source (not shown). The hose adapter  82  is selected from a group of adapters  82  that convert the diameter of the exit opening  86  to the proper size for the user&#39;s vacuum hose. The hose adapter  82  may be angled, as shown, or it may be straight. The barb  81  at the edge of the inlet  83  operates to retain the adapter  82  in the exit opening, as well as being a swivel that allows the outlet  85  to pivot in relation to the cover  170 A. A unique aspect of the adapter  82  is that the diameter and wall thickness of the outlet  85  is designed so that it can accept a male fitting from a 1.250 (ID) vacuum hose or it can accept the actual 1.500 hose over the outside of the outlet  85 . As discussed above, there could also be a relief vent/valve provided within the adapter  82  to relieve vacuum within the cover  170 A, if necessary. 
         [0036]    A series of plugs  73  are provided to the user. The plugs  73  can be selectively inserted into one or more of the air vents  75  when the door element [ 48 ] is opened. The vacuum source and amount of dust being created will determine whether and how many plugs  73  are used to plug air vents  75 .  FIG. 3  provides additional detail regarding the cover  170 A. 
         [0037]      FIG. 3  is a top view of the cover  170 A of the shield [ 100 A] of  FIG. 2 . The assembly is shown here as it would exit the mold in production. A peg element  40  is molded into the exhaust port  80 A at the exit opening  86 . This peg  40  is to be removed prior to the first use of the cover  170 A; its purpose is to provide the user with the ability to hold open the door element  48  without using his or her hands. This feature is discussed in additional detail below. 
         [0038]    As can be seen at the top of the cover  170 A (in this depiction), an integral door element  48  is molded into the cover  170 A. The door element  48  must be cut loose from the base  50  before it will open for zero clearance operations. There is a line of hinge apertures  41  that extend through the wall comprising the upper portion  72  of the base  50 . The hinge apertures  41  are in spaced relation, and are separated by hinge elements  46 , which are essentially strips of material molded into the upper portion  72  that are possibly somewhat thinner than the wall thickness of the rest of the upper portion  72 . The dashed line shown at the outer edges of the outer hinge apertures  41  denotes a “cut line  44 ,” along which the user must cut through the wall making up the upper portion  72  of the cover  170 A so that the door element  48  can be opened for zero clearance operations. 
         [0039]    There are also a pair of peg apertures  42 A,  42 B formed on either side of the door element  48  hinge (in this case centered on the middle hinge aperture  41 ). When the door element  48  is opened, the two peg apertures  42 A,  42 B will be in alignment so that the peg element  40  (once cut free from the exit opening  86 ) can be inserted through them to hold the door element  48  in the open position. The hinge [ 36 ] is discussed further below in connection with  FIG. 3 . 
         [0040]      FIG. 4  is a bottom view of the cover  170 A of  FIG. 3 . From this bottom side, the portion of the upper portion  72  wall that is thinner than the rest can be seen. This thinner portion is created as a channel formed in the wall of the upper portion—it is referred to as the hinge channel  38 . The hinge apertures  41  penetrate all the way through the upper portion, while the hinge elements  46  are not apertures, but rather are portions of the upper portion  72  that have a thinner wall thickness than the rest of the upper portion  72 . The two outer segments of the hinge channel  38  correspond to the cut line [ 44 ] discussed above in connection with  FIG. 3 . Because of the channel  38 , these portions thinner than the wall thickness of the rest of the cover  170 A. The thin wall thickness is highlighted as element  45 , but should be understood to be exemplary only—this element  45  simply identifies the hinge channel at a point where the thinner wall thickness is visible from below.  FIG. 5  depicts the functionality of the cover  170 A once the user has cut through the cover  170 A along the cut line [ 44 ]. 
         [0041]      FIG. 5  is a top view of the cover  170 A of  FIGS. 2 and 3  depicting the door element  48  in the opened position. As shown, the door element  48  has been folded all the way open until it is flat against the top of the upper portion  72 . In this position the cutting wheel  34  (depicted in hidden lines here) is exposed and is protruding through the cover opening  43  so that it can be used in a zero clearance situation. 
         [0042]    The door element  48  has rotated around the hinge element  46  until the two peg apertures  42 A,  42 B are in alignment. The user need simply cut through the bridge elements  32  interconnecting the peg  40  with the wall  30  of the exhaust port  80 A, and then insert the peg  40  through the peg apertures  42 A,  42 B in order to retain the door element  48  in the open position. An alternate view of this situation is shown in  FIG. 6 . 
         [0043]      FIG. 6  is a perspective view of the cover of  FIGS. 3-5  having the door element  48  in the opened position. Here, the peg element  40  has been cut free from the exhaust port  80 A, and is being inserted through the peg apertures  42 A,  42 B. If the user wishes to leave the door element  48  closed during use, he or she can remove the peg from the two apertures  42 A,  42 B and then pivot the door element  48  until it covers the side opening  26 . The peg element  40  can then be stored by inserting it into either the aperture on the door element  42 A, or the aperture on the upper portion  42 B. In this manner, the peg element  40  is readily on hand when needed. 
         [0044]    Those skilled in the art will appreciate that various adaptations and modifications of the just-described preferred embodiment can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.